

lECHMICAIi IiIBRAKY 


of the 


ARMED FORCES 
SPECIAL WEAPOSS PROJECT 

? - n - 3 < 


SUMMARY TECHNICAL REPORT 


OF THE 


NATIONAL DEFENSE RESEARCH COMMITTEE 


Manuscript and illustrations for this volume were prepared for pub- 
lication by the Summary Reports Group of the Columbia University 
Division of War Eesearch under contract OEMsr-1131 with the 
Office of Scientitic Eesearch and Development. This volume was 
printed and bound by the Columbia University Press. 

Distribution of the Summary Technical Eeport of NDEC- has been 
made by the War and Navy Departments. Inquiries concerning the 
availability and distribution of the Summary Technical Eeport 
volumes and microtilmed and other reference material should be 
addressed to the War Department Library, Eoom lA-522, The 
Pentagon, Washington 25, D. C., or to the Office of Naval Eesearch, 
Navy Departnient, Attention ; Eeports and Documents Section, 
Washington 25, D. C. 

Copy No. 

333 


This volume, like the seventy others of the Summary Technical 
Eeport of NDEC has been written, edited, and printed under great 
pressure. Inevitably there are errors which have slipped past Division 
readers and proofreaders. There may be errors of fact not known 
at time of printing. The author has not been able to follow through 
his writing to the final page proof. 

Please rei)ort errors to: 

.JOINT jn':SKAl{CH AND DEVELOPMENT DOAPD 
PPOGPAMS DIVISION (STO EPPATA) 

WASHINGTON 25, D. C. 


A master errata sheet will l)e conn)iled from these rei)orts and sent 
to recipients of tbe volume. 5h)ur help will make this book more 
useful to other readers and will be of great value in preparing any 
revisions. 


SUMMARY TECHNICAL REPORT OF THE TROPICAL 
DETERIORATION ADMINISTRATIVE COMMITTEE, NDRC 

VOLUME I 


TROPICAL DETERIORATION 
OF EQUIPMENT AND MATERIALS 


OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT 
VANNEVAR BUSH, DIRECTOR 

NATIONAL DEFENSE RESEARCH COMMITTEE 
JAMES B. CONANT, CHAIRMAN 

TROPICAL DETERIORATION ADMINISTRATIVE COMMITTEE 
G. J. ESSELEN, CHAIRMAN 


WASHINGTON, D. C., 1946 


NATIONAL DEFENSE RESEARCH COMMITTEE 


James B. Conant, Chairman 
Richard C. Tolman, Vice Chairman 
Roger Adams Army Representative^ 

Frank B. Jewett Navy Representative- 

Karl T. Compton Commissioner of Patents" 

Irvin Stewart, Executive Secretary 


^Army Representatives in order of service: 

Maj. Gen. G. V. Strong- Col. L. A. Denson 

Maj. Gen. R. C. Moore Col. P. R. Faymonville 

Maj. Gen. C. C. Williams Brig. Gen. E. A. Regnier 
Brig. Gen. W. A. Wood, Jr. Col. M. M. Irvine 
Col. E. A. Routheau 


^Navy Representatives in order of service: 

Rear Adm. H. G. Bowen Rear Adm. J. A. Furer 

Capt. Lybrand P. Smith Rear Adm. A. H. Van Keuren 

Commodore H. A. Schade 
'^Commissioners of Patents in order of service: 
Conway P. Coe Casper W. Ooms 


NOTES ON THE ORGANIZATION OF NDRC 


The duties of the National Defense Research Committee 
were (1) to recommend to the Director of OSRD suitable 
projects and research programs on the instrumentalities 
of warfare, together with contract facilities for carrying 
out these projects and programs, and (2) to administer 
the technical and scientific work of the contracts. More 
specifically, NDRC functioned by initiating research 
projects on requests from the Army or the Navy, or on 
requests from an allied government transmitted through 
the Liaison Office of OSRD, or on its own considered 
initiative as a result of the experience of its members. 
Proposals prepared by the Division, Panel, or Committee 
for research contracts for performance of the work in- 
volved in such projects were first reviewed by NDRC, and 
if approved, recommended to the Director of OSRD. Upon 
approval of a proposal by the Director, a contract permit- 
ting maximum flexibility of scientific effort was arranged. 
The business aspects of the contract, including such 
matters as materials, clearances, vouchers, patents, pri- 
orities, legal matters, and administration of patent mat- 
ters were handled by the Executive Secretary of OSRD. 

Originally NDRC administered its work through five 
divisions, each headed by one of the NDRC members. 
These were: 

Division A — Armor and Ordnance 
Division B — Bombs, Fuels, Gases, & Chemical Problems 
Division C — Communication and Transportation 
Division D — Detection, Controls, and Instruments 
Division E — Patents and Inventions 


In a reorganization in the fall of 1942, twenty-three 
administrative divisions, panels, or committees were 
created, each with a chief selected on the basis of his 
outstanding work in the particular field. The NDRC mem- 
bers then became a reviewing and advisory group to the 
Director of OSRD. The final organization was as follows: 

Division 1 — Ballistic Research 

Division 2 — Effects of Impact and Explosion 

Division 3 — Rocket Ordnance 

Division 4 — Ordnance Accessories 

Division 5 — New Missiles 

Division 6 — Sub-Surface Warfare 

Division 7 — Fire Control 

Division 8 — Explosives 

Division 9 — Chemistry 

Division 10 — Absorbents and Aerosols 

Division 11 — Chemical Engineering 

Division 12 — Transportation 

Division 13 — Electrical Communication 

Division 14 — Radar 

Division 15 — Radio Coordination 

Division 16 — Optics and Camouflage 

Division 17 — Physics 

Division 18 — War Metallurgy 

Division 19 — Miscellaneous 

Applied Mathematics Panel 

Applied Psychology Panel 

Committee on Propagation 

Tropical Deterioration Administrative Committee 


IV 


NDRC FOREWORD 


AS EVENTS of the years preceding 1940 revealed more 
and more clearly the seriousness of the world 
situation, many scientists in this country came to 
realize the need of organizing scientific research for 
service in a national emergency, liecommendations 
which they made to the White House were given care- 
ful and sympathetic attention, and as a result the 
National Defense Eesearch Committee [NDEC] was 
formed by Executive Order of tlie President in the 
summer of 1940. The members of NDRC, appointed 
by the President, were instructed to supplement the 
work of the Army and the Navy in the development 
of the instrumentalities of war. A year later, upon the 
establishment of the Office of Scientific Research and 
Development [OSRD], NDRC became one of its units. 

The Summary Technical Report of NDRC is a 
conscientious effort on the part of NDRC to summa- 
rize and evaluate its work and to present it in a useful 
and permanent form. It comprises some seventy vol- 
umes broken into groups corresponding to the NDRC 
Divisions, Panels, and Committees. 

The Summary Technical Report of each Division, 
Panel, or Committee is an integral survey of the work 
of that group. The first volume of each group’s report 
contains a summary of the report, stating the problems 
presented and the philosophy of attacking them, and 
summarizing the results of the research, development, 
and training activities undertaken. Some volumes may 
be ^^state of the art” treatises covering subjects to 
which various research groups have contributed in- 
formation. Others may contain descriptions of devices 
developed in the laboratories. A master index of all 
these divisional, panel, and committee reports which 
together constitute the Summary Technical Report 
of NDRC is contained in a separate volume, which 
also includes the index of a microfilm record of per- 
tinent technical laboratory reports and reference 
material. 

Some of the NDRC-sponsored researches which had 
been declassified by the end of 1945 were of sufficient 
popular interest that it was found desirable to report 
them in the form of monographs, such as the series 
on radar by Division 14 and the monograph on sam- 

In contrast to the information on radar, which is 
of widespread interest and much of which is released 
to the public, the research on subsurface warfare is 
largely classified and is of general interest to a more 
restricted group. As a consequence, the re])ort of 

Division 6 is found almost entirely in its Summary 

Technical Report, which runs to over twenty volumes. 

The extent of the work of a division cannot therefore 
be judged solely by the number of volumes devoted 
to it in the Summary Technical Report of NDRC : 
account must be taken of the monographs and avail- 
able reports published elsewhere. 

The size of the Tropical Deterioration Administra- 
tive Committee, one of the smallest of the NDRC 
groups, constituted no measure of its importance or 
accomplishments. The value of the Committee’s work 
extends beyond the war into the peace. Under the 
chairmanship of Gustavus J. Esselen, the members 
of the Committee opened up a new field of knowledge 
when they undertook a program of fundamental re- 
search on the deterioration, under tropical conditions, 
of equipment and supplies — particularly lenses and 
other components of cameras and optical instruments, 
films, textiles, resins, and plastics. 

Though the end of the war found the Committee’s 
studies still incomplete, many significant preliminary 
results had been obtained, extensive collections of fungi 
and bacteria broadened our knowledge of the relation- 
ships of these organisms to deterioration processes, 
and effective applications of fungicides and protective 
methods had been developed. An indication of the 
importance attached by the Armed Services to the 
work is the fact that six of the projects undertaken by 
the Committee are being continued by the Army and 

Navy. 

The Summary Technical Report of the Committee 
has been prepared under the direction of the Chair- 
man and has been authorized by him for publication. 

This report is a record of enterprise and vision in 
investigating a hitherto unexplored field of research, 
and of work in laying a foundation of fact for future 
development. For the C^ommittee’s achievements, we 
express our deep gratitude. 

pling inspection by the Applied Mathematics Panel. 
Since the material treated in them is not duplicated 
in the Summary Technical Report of NDRC, the 
monographs are an important part of the story of 
these aspects of NDRC research. 

Vannevar Bush, Director 

Office of ScienUfic Eesearch and Development 

J. B. CoNANT, Chairman 

National Defense Eesearch ComniiLtee 


V 











T hk riUME OBJECTIVES of the Army and Navy in re- 
questing the NDRC to undertake a project on the 
prevention of tropical deterioration were to effect co- 
ordination hetween the individual programs of the 
military agencies and to arrange for additional studies 
which were needed. Since the primary purpose of this 
report is to summarize the technical accomplishments 
in the studies which were nndertaken, attention is 
given in this foreword to the hackgronnd for the ad- 
ministrative organization which was primarily respon- 
sible for the successes in coordinating individual and 
separate investigations. 

In Fehrnary 19-14, a conference was held attended 
by 101 Army and Navy officers and OS HD represen- 
tatives. Inasmuch as large scale activities in tropical 
regions had presented a serious problem in the loss of 
equipment through tropical deterioration and an even 
more serious problem in the iinserviceability of equip- 
ment needed for use, the conference was held in order 
that various interests in the problem might he stated 
and in order to consider an organization through 
which coordination of all investigations on the prob- 
lem could he realized. 

To effect coordination and guide all the interrela- 
tionships of studies pertinent to the problem it was 
proposed that there be established a Joint Army-Navy- 
NDHC Tropical Deterioration Steering Committee, 
consisting of three members each from the Army, 
Navy, and the NDRC. This proposal was formally 
})resented with a Project Request for Army-Navy 
Project 14. During most of its activity, the following 
were members of the Tropical Deterioration Steering 
Committee: For the Army: Lt. Col. Don Bronse, 
Colonel W. J. Renn, and Major F. P. Willcox; for 
the Navy : Lt. Commander II. W. Gilbert, Commander 
A. E. jMacGee and Captain R. 0. Phillips; for the 
NDRC : Theodore Dunham, dr., Selman A. Waksman, 
and Gnstavns J. Esselen, Chairman. 

The Tropical Deterioration Administrative Com- 
mittee, having the usual administrative and technical 
functions of an NDRC division, was established on the 
recommendation of the Steering Committee to arrange 
for various contracts which were needed and to super- 
vise their contract activities. Subsequently, subcom- 
mittees of the Administrative Committee were organ- 
ized to insure that important problems presented in 
various broad fields would he covered. Subcommittees 
were appointed as follows : Coordination of Test Meth- 


ods; Packaging; Electrical and Electronic Equip- 
ment; Textiles and Cordage; Optical Instruments; 
Synthetic Resins, Plastics and Plasticizers; and Pho- 
tographic Equipment and Supplies. In addition to 
OSRD appointees. Army and Navy personnel served 
as members of most of the subcommittees. The Service 
personnel were chosen from Service branches having- 
direct interests in the particular subjects. 

The results of the various research projects which 
were recommended to round out the tropical deteriora- 
tion program are summarized in this report. However, 
a major activity of the Tropical Deterioration iVdmin- 
i strati ve Committee — the distribution of information 
on tropical deterioration — is not reviewed. For this 
purpose, there was established the Tropical Deteriora- 
tion Information Center. All available reports, both 
foreign and domestic, related to tropical deterioration 
were deposited there and abstracts of these were pub- 
lished in the semi-monthly Tropical Deterioration 
Bulletin. From time to time additional reports on spe- 
cial subjects were also prepared and distributed. These 
various publications of the Information Center were 
distributed to a regular mailing list of over 250 Army 
and Navy officers and laboratories, and Allied labo- 
ratories. 

Direct Service liaison was accomplished through a 
rather large list of appointed liaison officers. In addi- 
tion to the distribution of reports and meeting minutes 
to these liaison officers, special meetings were held 
with them to review the progress which had been 
made in the various studies and to obtain the view- 
points of the various branches of the Services toward 
the problems at hand. Needless to say, the Service 
members of the subcommittees fulfilled an important 
liaison function with many branches of the Army and 
Navy. In this regard, the publications of the Informa- 
tion Center were particularly effective in that they 
served to keep all Servii'e groups informed of current 
])rogress in the field. 

The investigations on optical instruments which are 
reported were initiated during 1941 and 1942 by Sec- 
tion 10. 1 of the NDRC under Project OD-43. These 
studies were transferred to the Tropical Deteriora- 
tion Administrative Committee shortly after it was 
organized. While the project was under the auspices of 
Section 16.1 methods were developed for the protec- 
tion of optical instruments by the use of volatile and 
contact fungicides and the Panama Test Station was 


FOREWORD 


viii 

established. Since the transfer of this work, further 
stndies of optical instruments have been made, par- 
ticularly long time field exposures and research on 
improved sealing compounds. The program of the 
Panama Test Station has been extended to include, 
in addition to studies on optical instruments, expo- 
sure tests on a wide variety of other materials. 

The Japanese surrender found the different con- 
tract activities in various stages of completion, but 
they were deemed of sufficient importance by the Army 
and Xavy that six of the seven active contracts at that 
time were continued by interested Service branches. 

The significance and importance to the Armed Serv- 
ices of our coordinated program is indicated by the 
fact that in accordance with a recommendation of the 
Tropical Deterioration Steering Committee, there has 
been established a Joint Army-Navy Committee hav- 
ing official standing to coordinate investigations on 
tropical deterioration and the prevention thereof. 

The success of our program was due in a large meas- 
ure to the fine cooperation which was shown by all 
those who participated in the work. The members of 
the Steering Committee, both individually and collec- 
tively, deserve recognition for the valuable services 
which they rendered. The expert services of the mem- 
bers of the Administrative Committee and the Sub- 


committee Chairmen are also acknowledged. Major 
credit for the accomplishments in research studies and 
contract activities is given to Dr. Elso S. Barghoorn, 
Jr., Office of Field Service; Dr. W. Cf. Hutchinson, 
University of Pennsylvania ; Dr. William H. Weston, 
Harvard University ; Dr. Glenn A. Greathouse, The 
George Washington University; Dr. Herbert W. 
Peuszer, Soil Conservation Service, U. S. Department 
of Agriculture; Mr. H. F. Robertson, Bakelite Cor- 
poration; Dr. Ralph K. Witt, The Johns Hopkins 
University; and Dr. R. H. Luce, Rensselaer Poly- 
technic Institute. The interest and assistance of Mr. 
N. A. Whiffen and Dr. M. F. Day, Australian Scien- 
tific Research Liaison Office and of Mr. B. N. P. Hut- 
chesson, British Commonwealth Scientific Office, in 
matters concerning Australian, Canadian, and United 
Kingdom studies is also greatly appreciated. 

Special appreciation is extended to Dr. Charles 
Heimsch, Technical Aide and Lt. Wesley H. Suit, 
USNR, Special Assistant to the Chairmen for their 
unusually fine services in handling the many admin- 
istrative and technical details connected with the work 
of this Committee. 

Gustavus J. Esselen 
Chairman, Tropical Deterioration 
Administrative Committee 


PREFACE 


T hk report presented in this volume summarizes 
the technical accomplishments in the studies which 
were undertaken by the Tropical Deterioration Ad- 
ministrative Committee. No attempt has been made 
to discuss the important aspects of the Committee’s 
work relative to the distribution of information to the 
branches of the Army and Navy which were concerned 
with tropical deterioration problems. This constituted 
an important aspect of the Committee’s program to 
coordinate investigations on the problems of tropical 
deterioration conducted by the individual branches of 
the Army and Navy. 

The status of tropical deterioration problems as they 
pertain to specific types of materials has previously 
been summarized in a number of reports which have 
been issued by the Tropical Deterioration Administra- 
tive Committee. The classes of materials for which 
such reports have appeared are as follows ; Optical in- 
struments; textiles; synthetic re.sins, plastics and plas- 
ticizers; and, photographic equipment and supplies. 
In addition to these, a report has also appeared which 
summarizes and evaluates the various test methods 
which have proved to be useful in determining the 
suitability of materials for tropical service. These re- 
ports have served as the primary basis and background 
for certain of the chapters in this volume; for in- 
stance, Chapter 5 is an abridged version, as approved 
for publication, and which appeared in the April 1946 
issue of Modern Plastics, of a report of the Committee 
which discusses the problems of fungal growth on 
synthetic resins, plastics, and plasticizers. Also, Chap- 
ter 6 is almost entirely based on the report which sum- 
marizes the activities of the Subcommittee on Photo- 
graphic Equipment and Supplies. Those discussions 


which are not based on previous summary reports are 
organized either to relate studies which have been re- 
ported independently or to give emphasis to informa- 
tion which has been only recently reported. 

A considerable number of reports on tropical dete- 
rioration studies have appeared from Army and Navy 
Laboratories as well as from the Allied Governments 
of Australia, Canada, and the United Kingdom, and 
no attempt has been made to summarize or to include 
as bibliographic entries all of those which were in any 
way related to the studies of the Tropical Deteriora- 
tion Administrative Committee. However, reference is 
made to certain of these reports which bear particular 
relation to the studies reported in this volume. 

In presenting this summary of the investigations of 
the Tropical Deterioration Administrative Committee, 
a highly technical background on the part of the reader 
is not presupposed. The aim and objective of the Com- 
mittee’s program and the results which were achieved 
should be clear to all who are aware of the problems 
which tropical use imposes upon the serviceability of 
equipment and supplies. For detailed information and 
results of the investigations which have been made, the 
reader is referred to the various reports which are 
included as bibliographic entries. 

Acknowledgment is made to all the investigators 
who are responsible for the studies reported here for 
their ideas and information which have been drawn 
upon freely. Their experience and broad acquaintance 
with the problems at hand have been a valuable con- 
tribution to this report. 

Charles Heimsch 
Editor 


IX 



* 

f 



\ 


CONTENTS 


CIIAPTEIJ 


PAGE 


Siinimarv 1 

1 Introduction o 

2 Organisms Associated with Tropical Deterioration ... 7 

3 Prevention of Deterioration of Optical Instruments . . 18 

4 Tropical Deterioration of Textiles 27 

5 The Problem of Fungal Growtli on Synthetic Pesins, 

Plastics, and Plasticizers 40 

6 Tropical Deterioration of Photographic Equipment and 

Supplies 40 

7 Tropical Deterioration of Electric and Electronic Equip- 
ment 57 


8 Coordination of Test Methods 02 

9 Pesnlts of Testing Materials under Tropical Conditions . GO 

10 Pecommendations for Future Work 78 

Bibliography 81 

OSPD Appointees 84 

Contract Numbers 8G 

Service Project Numbers 87 

Index 80 




mitjw 


iciLiiJuimi 


r 


} 


SUMMARY 


W ITH THU Service request for the project on the 
prevention of tropical deterioration of equipment 
and supplies, it was recommended that there be estab- 
lished a joint Army-Xavy-NDIiC Tropical Deteriora- 
tion Steering Committee to coordinate investigations 
on the subject which were then underway and to 
arrange for new investigations as they were needed. 
Later, upon the recommendation of the Steering Com- 
mittee, there was organized by the OSED the Tropical 
Deterioration Administrative Committee [TDAC], 
having the usual administrative and technical func- 
tions of an XDEC division, to arrange for various 
contracts which were needed and to supervise the con- 
tract activities. The studies which are reported herein 
are those which were under the supervision of the 
Administrative Committee. 

In tropical Avarfare, equipment and supplies are 
usually exposed to heavy rainfall and high relative 
humidity which together introduce numerous problems 
relative to the performance and serviceability of mate- 
rials, AA'hereas these problems are of little or no con- 
cern in temperate regions. Tropical climatic factors 
are important in themseh^es in that most items of 
equipment and supplies Avhich are not protected 
against them are subject to severe damage; but they 
are also important in that they furnish ideal condi- 
tions for the growth and dcA^elopment of microorgan- 
isms (fungi, actinoniycetes, and bacteria). The im- 
portance of these microorganisms lies in the fact that 
collectively they are able to attack a wide range of 
basic materials and thus cause the destruction or 
deterioration, total or partial, of military items. 

The importance of microorganisms in the tropical 
deterioration of military items Avas estalDlished in field 
studies conducted by the Australians during the early 
stages of the Pacific phase of World War IT. HoAvever, 
this early information and that Avhich continued to 
l)ecome available later tended to emphasize the nature 
and extent of damage to materials rather than the fun- 
damental reasons for the damage or hoAV it occurred. 
Early in the program of TDAC, plans Avere initiated 
for a Science Mission to Pacific areas to obtain funda- 
mental information on the causes of tropical deteriora- 
tion with emphasis on determining the role of micro- 
organisms and the mechanism by AAdiich damage is 
done, including the sequence of changes AAdiere more 
than one organism is inA-oh^ed. Additional studies re- 


lated to these Avere also planned. It Avas necessary, after 
final arrangements for departure Avere made, to cancel 
these plans; hoAvever, it Avas arranged for a modified 
program to be undertaken in Panama. 

In this report there are revieAA^ed the activities of 
the Tropical Fungus Culture Collection [TFCC], 
AA’hich Avas organized to receive, maintain, and identify 
the fungi associated Avith deterioration isolated in the 
course of these Panama studies. The major source of 
these organisms Avas an extensive set of experimentally 
treated textile samples Avhich AA^ere studied intensively 
Avith respect to the influence of physical and biological 
factors in the deterioration process. After fungus cul- 
tures AA'ere receiA^d from Panama, they Avere purified, 
AAdien necessary, and their identity Avas determined in 
order to provide significant information for analysis 
and correlation Avith other studies. Fungi AA^ere also 
isolated in Panama from natural sources, such as de- 
caying plant remains, etc., in order to understand fully 
the origin and distribution of the forms important in 
textile deterioration. Textile materials AAdiich had been 
sterilized AA^ere also subjected to attack by fungi under 
natural conditions in order to differentiate betAA^een 
those fungi derived from local sources (Panama) and 
those fungi Avhich might have been present on the ex- 
perimental panels before and during shipment. 

In all, approximately -1,500 fungus cultures Avere 
deposited in the Tropical Fungus Culture Collection. 
As stated above, these Avere derived for the most part 
from the Panama field studies. Fungi present in the 
collection other than those from Panama AA^ere ob- 
tained primarily from the Australian Mycological 
Panel, Avhich supplied a set of the most important 
organisms isolated in XeAv Guinea field studies, and 
various Army and Navy laboratories engaged in 
trojiical deterioration studies. 

The task of maintaining such a large collection of 
living fungi Avas one of tremendous proportions. At 
any given time a majority of the cultures Avere kept 
in an actively groAving condition. For purposes of 
long-time storage, hoAvever, cultures Avere preserved 
in a dormant condition by a lyophilization process. 
This consists of freezing instantaneously a small quan- 
tity of fungus spores suspended in horse serum or 
skim milk in small glass tubes, after AAdiich the spore 
suspension is dried by pumping off Avater vapor under 
vacuum until a dry pellet is formed. AYhile under 


1 




2 


SUMMARY 


vacuum the cflass tiibing is fused off aud tlie coutaiuer 
with pellet is hermetically sealed. This method of 
preservation is relatively ]iew, hut it is known tliat 
fungi will survive at least five years storage under 
these conditions. The use of this method hy TFCC 
represented the first attempt to apply it in such an 
extensive fashion to such a wide range of different 
fungi. Many cultures which were not adaptable to 
preservation hy this technique for a variety of reasons 
were successfully conserved in a dormant condition 
hy covering the active cultures with sterile mineral oil. 

By the application of these methods for a long-time 
storage, this extensive collection of fungi has been 
preserved for future study. AVithout doubt it repre- 
sents the largest collection of tropical fungi which has 
ever been assembled in the living condition and the full 
potentialities of these organisms still remain to he 
exploited. There is every reason to believe that upon 
intensive study these forms will yield information 
which will he valuable to agriculture, medicine, and 
other fields of science. 

Although efforts were concentrated on maintaining 
and identifying the fungi in the collection, certain 
important observations on their growth and behavior 
were possible. An analysis of the cultures indicates 
those forms which are most important in textile 
deterioration in Panama, permits comparison with 
those fungi which have been reported as significant 
in textile deterioration in Panama, and permits com- 
parison with those fungi which have been reported 
as significant in textile deterioration in other geo- 
graphical locations. It has been possil)le to compare 
the Panama fungi with collections from Florida, 
India, and New Guinea and other Pacific regions. The 
significance of agreement or disagreement in these 
comparisons can only be determined by future detailed 
analyses involving precise comparative studies. 

In conjunction with the Panama field studies on 
deterioration of textiles hy fungi, studies were also 
conducted to determine the extent to which these 
materials were attacked by bacteria under natural 
conditions. The bacteria which were obtained in these 
studies served as the nucleus for a Bacteria Culture 
Collection [BCC] maintained by TDAC. To these 
bacteria cultures from Panama were added many 
cultures isolated by Quartermaster laboratories in 
studies of deteriorated materials returned primarily 
from Pacific areas. The total number of bacteria cul- 
tures on hand was a])proximately 1,100. 

For practical purposes, the bacteria were classified 


into two main types according to their physiological 
capacities and effects on the deterioration of fabrics: 
(1) those capable of destroying cellulose, and (2) 
those incapable of destroying cellulose. Oidy limited 
specific identifications were able to be made in each 
group. 

The significance which cellulose decomposing bac- 
teria may hold in the deterioration of fabrics is ob- 
vious, and in the Panama field studies these forms 
were present in large numhers on fabrics which showed 
marked evidence of deterioration. Noncellulose de- 
composing bacteria were present on experimental fab- 
rics after four to six weeks of air exposure in such 
large numbers that it seems they may play an im- 
portant part in the initial stage of deterioration of 
treated fabrics. It is suggested that these noncellulose 
decomposing bacteria may cause destruction of the 
treating agents which are applied to fabrics, thus caus- 
ing a reduction in fungicidal value and possibly in- 
creasing chemical deterioration of the fabric. Addi- 
tional studies are necessary before this problem can be 
further clarified. 

In addition to the information on the biological de- 
terioration of textiles which resulted from the Panama 
field studies, valuable data on other aspects of the 
performance of textiles in the tropics were also ob- 
tained. It was possible to determine the efficacy of the 
various experimental fungicides under different con- 
ditions of exposure and to relate their performance to 
the physical factors of the environment. The observa- 
tion that sun exposure promotes chemical deterioration 
of fabrics by causing a breakdown of certain fungicides 
is important, particularly in that copper naphthenate, 
the fungicide most widely used on tentage and tar- 
paulins, was among those most seriously affected when 
it is not adequately protected from sunlight hy screen- 
ing pigments. Evidence was also obtained that certain 
ingredients of the water repellent finish, such as 
aluminum acetate, when applied to heavy fabrics were 
subject to the effects of sunlight with subsequent pho- 
tochemical deterioration of the fabric. 

Tlie deterioration of optical instruments in tropical 
service was among the problems which proved to he 
serious in early Pacific operations. Deterioration of 
optical instruments may he due to moisture alone or 
moisture in combination with fungus. Many materials 
ordinarily used in optical instruments are capable of 
su})porting fungus growth ; furthermore, organic debris 
such as a dead insect or even a fingerprint can furnish 
nutrients which will support sufficient fungus growth 


SUMMARY 


3 


to be troublesome aiul decrease the etficieiicy of an 
instrument. If actively growing fungi are allowed to 
persist within an instrument for extended periods, 
permanent damage to lenses, prisms, and other parts 
can result. 

The construction of many optical instruments, par- 
ticularly old models, many of which were necessarily 
used, is such that moisture readily gains access to the 
interiors of the instruments with lluctuations in tem- 
perature and resulting changes in air pressure. In 
addition to the direct effects of the moisture within 
instruments, it provides relative humidities adequate 
for the growth of fungi. Prevention of moisture de- 
terioration can only be achieved by virtually complete 
sealing of all cracks and openings. 

An adequate method for controlling fungus growth 
within optical instruments Avas developed. In field 
trials under drastic jungle conditions in Panama this 
method has kept binoculars free from fungi for over 
21 months. This method consists of applying a mixture 
of 50 per cent of the fungicide Cresatin (metacresyl 
acetate) and 50 per cent ethyl cellulose enclosed in a 
small aluminum capsule Avith minute openings. The 
capsule is attached Avith cement Avithin the instrument 
out of the paths of light rays. The fungicide is volatile 
and the small openings alloAv^ only gradual escape of 
the fungicide from the reservoir Avithin the capsule. 

Another method using a contact fungicide, Thanite 
(fenchyl thiocyanoacetate), rather than a volatile fun- 
gicide for the control of fungi in optical instruments 
is also described. 

With the importance Avhich Avas given to proper 
sealing of instruments and the knoAvledge that the 
compound Avhich Avas most Avidely used Avas not entirely 
satisfactory, a search Avas made for a more suitable 
substitute. The most promising of the experimental 
compounds A\diich AA'ere tried had as their basic ingre- 
dient a proprietary thermoplastic resin of an undis- 
closed formulation. 

This report also rcvicAv^s the prohlem of fungal 
groAvth on synthetic resins, })lastics, and plasticizers 
and discusses the problem Avuth reference to the sus- 
ceptibility of pure resins to fungal attack, the suscepti- 
bility of plasticizers and other plastic components to 
fungal attack, the susceptibility of complete plastic 
compositions to fungal attack, the effect of fungal 
groAvth on properties of plastics, and the results of 
experiments in Avhich fungicides had been added to 
plastics. Practically no information on the tropical 
deterioration of plastics existed prior to World War TT, 


and investigationsAvere organized byTDACto broaden 
and increase knoAvledge of the performance of plastics 
under tropical conditions. The results of these inves- 
tigations are cited in the revieAV of the general problem. 
An important question on Avhich further information 
is necessary before the problem can be fully solved 
concerns the precise effect of fungus groAvth on plastic 
materials. It is aatII established that surface groAvth 
on plastics used in electric and electronic equipment 
is deleterious in that it affects the electrical properties 
of the plastics. IIoAA^ever, the effect of fungus groAvth 
on the physical and mechanical properties of plastics 
requires further elucidation. 

Much attention Avas devoted to the tropical deterio- 
ration of photographic equi])ment and supplies. The 
recommendations to prevent the deterioration of films, 
chemicals, and cameras and accessories are revieAA^ed. 
With these items, particularly film, proper packaging 
for tropical service is an essential. The problem of 
fungus attack of processed films Av^as thoroughly in- 
vestigated. The importance of the ])rohlem rests in 
the fact that negatives, Avhich serve as important his- 
torical records of units, campaigns, etc., as AA^ell as 
individual medical records, are highly subject to 
fungus attack inasmuch as the gelatin emulsion is an 
excellent nutrient for fungus. A fungicidal treatment 
Avhich can be applied to processed films in a dip bath 
AA'as developed and this method sIioaa^s excellent prom- 
ise over various other methods Avhich AA^ere tried. 
IiiA’estigations revealed that cautious use of lacquers 
containing the mercurial fungicide Merthiolate is 
effectiA’e in controlling fungus groAvth on camera parts. 
Cautious use of such lacquers is indicated because 
fungicides containing mercury liaA^e been shoAvn to 
have an adverse effect on photographic emulsions. In- 
novations in design of cameras so as to permit ready 
interchange and serviceability of parts AA^ould markedly 
decrease the incidence of tro])ical deterioration in these 
items, particularly Avdicn accompanied by adequate 
tropical storage facilities and a proper maintenance 
program. 

The tropical deterioration of electric and electronic 
equipment presented many problems. In achieving a 
solution to these, the adverse effect of moisture and 
fungus on components and parts of such equipment 
requires control. The fundamental studies of TDAC 
relating to these problems are summarized. Many 
questions and problems arose concerning the use of 
fungicidal lacquers and varnishes as a moisture bar- 
rier and as a protection against fungus on such equip- 


4 


SUMMARY 


ment. As the result of a Service request to settle some 
of these points of conflict, investigations to determine 
the effects of fungus growth on hookup wire were 
organized. Closely related studies on the long-range 
effects of moisture and fungus on electric insulating 
materials were also undertaken. A survey of existing 
information indicated tliat considerable data were 
available on the effects of moisture on electric insulat- 
ing materials after exposure for short periods, but 
little or no information was available on the perform- 
ance of such materials in exposures of long duration 
nor were the results related to effects of fungi. Tt is 
expected that with separate evaluation of the effects 
of moisture and fungus upon various types of plastics 
used as insulating materials, the information will per- 
mit a more realistic interpretation of the performance 
of these materials under tropical conditions, and fur- 
nish a working basis for selection of high-quality ma- 
terials in design of new equipment for tropical service. 

The investigations on the coordination of test meth- 
ods which are summarized were undertaken by TDAC 
because there was no uniformity or general agreement 
as to test methods for evaluating the suitability of 
materials for tropical service, and it was often impos- 
sible to duplicate test results in different laboratories. 
It was, therefore, obviously a prime essential to de- 
velop standard conditions for tests, which could be 
agreed upon by all laboratories and thus permit du- 
plication of results on a given sample regardless of the 
laboratory in which it was tested. Investigations were 
conducted to determine suitable test methods for 
hookup wires, coating materials, such as lacquers and 
varnishes, and plastics. As a result of these investi- 
gations, test methods were recommended for standard 
use in evaluating the fungus resistance of these mate- 
rials. Extensive studies were also conducted on cer- 
tain aspects of textile testing using pure cultures of 


test fungi. Detailed investigations were also made of 
various biological factors in determining the fungus 
resistance of plastics. 

In addition to conducting fundamental studies on 
various aspects of tropical deterioration problems, 
TDAC organized and carried out an extensive pro- 
gram of testing materials for the Army and Navy 
under natural tropical conditions in Panama and 
under simulated tropical conditions in a tropical house 
at the University of Pennsylvania. The materials ex- 
posed in Panama numbered over 15,000 individual 
items, and the materials exposed at the University of 
Pennsylvania numbered over 1,300 individual items. 

Kecomniendations concerning problems which arc 
still in need of investigation are given for the follow- 
ing materials: textiles and cordage; electric and elec- 
tronic equipment; synthetic resins, plastics, and plas- 
ticizers; and photographic equipment and supplies. 
These recommendations Avere proposed by the several 
subcommittees Avhich study the problems for each 
of the above classes of materials. 

At the time of the Japanese surrender, valuable pre- 
liminary results had been obtained from the studies 
of TDAC which were in progress, but none of the 
studies had reached the stage at which they could be 
considered as complete. It is gratifying to report that 
six of the seven projects which Avere underAvay at the 
close of hostilities AA^ere deemed of sufficient impoi'tancc 
to AA'arrant their continuation by various groups of the 
Armed Services. The significance and importance to 
the Armed Services of the cooixlinated program Avhich 
AA^as organized during AYorld War II is indicated 
by the fact that in accordance Avith a recommendation 
presented to the Army and Navy, there has been 
established a Joint Army-Navy Committee to coordi- 
nate investigations on tropical deterioration and the 
prevention thereof. 


Chapter 1 

INTRODUCTION 


11 PROBLEMS PRESENTED BY 
TROPICAL WARFARE 

W HEN MiLiTAEY OPERATIONS are coiiductecl ill 
tropical regions, equipment and supplies are sub- 
jected to climatic conditions far different from those 
of temperate regions. The heavy rainfall of many 
tropical areas and the continuously high relative 
humidity of most tropical areas introduce numerous 
considerations and problems relative to the perform- 
ance and serviceability of materials in tropical war- 
fare whereas these considerations and problems are of 
little or no concern in temperate regions. Tropical 
warfare demands that most items of materiel be ade- 
quately protected against the effects of moisture. This 
protection is necessary not only while items are in 
use, but also during the preceding period of transit 
and storage. Most items of equipment and supplies 
which are not protected against the effects of moisture 
are subject to severe damage. 

Not only are tropical climatic factors important in 
themselves, but it is perhaps even more significant 
that they furnish almost ideal conditions for the 
growth and development of microorganisms. Included 
among the microorganisms important in this respect 
are the thousands of forms of fungi, actinomycetes, 
and bacteria. The importance of these various micro- 
organisms lies in the fact that collectively they are 
able to attack a wide range of basic materials and thus 
cause the destruction or deterioration, total or partial, 
of military items. Furthermore, by virtue of the fact 
that these microorganisms are able to obtain nourish- 
ment from organic debris present on materials such 
as glass and metals, they are able to grow on these 
materials and, by their presence, cause serious damage. 
The damage to lenses and prisms of optical instru- 
ments which is discussed in Chapter 3 has been par- 
ticularly serious. 

12 EARLY STUDIES BY AUSTRALIAN 
GOVERNMENT 

Studies on the prevention of tropical deterioration 
of materiel were undertaken by the Australian gov- 
ernment in the early stages of the Pacific phase of 


World War II. These early investigations included 
field studies in New Guinea by a scientific mission of 
the Scientific Liaison Bureau.^ The observations which 
were made on the performance of stores and equip- 
ment under field conditions in New Guinea served as 
an important source of information for the tropical 
deterioration program of the military agencies in the 
United States. 

13 EARLY STUDIES IN THE 

UNITED STATES 

It is beyond the scope of this report to review the 
programs of the military agencies which had as their 
objective the protection of materials against tropical 
deterioration. It will suffice to point out that by 1944 
various branches of the Army and Navy had extensive 
programs underway. Furthermore, there had resulted 
from these studies many treatments which were effec- 
tive in reducing the effects of tropical exposure and 
thereby extending the service life of equipment. 

14 STUDIES OF THE TROPICAL 
DETERIORATION ADMINISTRATIVE 

COMMITTEE 

The studies of the Tropical Deterioration Admin- 
istrative Committee [TDAC] which are reported here 
supplemented the individual programs of the branches 
of the Army and Navy by giving attention to prob- 
lems upon which information was not available or by 
providing additional information on studies which 
were then underway. 

All phases of the TDAC investigations are reported 
in the following chapters. A background for the in- 
vestigations undertaken is presented with a discussion 
of each class of material. It will be noted that no 
consideration is given to the general and important 
subject of packaging. From the viewpoint of preven- 
tion of tropical deterioration, packaging methods are 
important in that protection against the effects of 
moisture during periods of transit and storage must 
be given. Attention was given to these problems by 
the Subcommittee on Packaging which surveyed this 
particular subject to determine the extent to which 
the problem of moisture-resistant packaging was al- 
ready being investigated. This subcommittee reported 


5 


6 


INTRODUCTION 


that the preliminary work with a view to develop 
water-resistant packages had ])een practically com- 
pleted by both the Army and Navy, and that it was 
then largely a matter of putting the resulting recom- 
mendations into effect, and the few details which still 
remained to be handled were being adequately cared 
for by other agencies. As a result of this report, no 
investigations on packaging materials or methods 
were organized. 

Tn the initial organization of the TDAC program, 
the desirability and advantage of field studies in 
tropical regions were recognized. Since there was no 
basis upon which to assume that the climatic and 
biological factors of all tropical regions were identical, 
it was apparent that the greatest contribution to the 
tropical deterioration program could he derived from 
studies conducted in Pacific regions where equipment 
and supplies would find greatest use. Such studies 
were particularly desirable in that precise information 
of the processes of deterioration was only meager — 
reports which had been made emphasized the nature 
and extent of damage rather than the fundamental 
reasons for the damage or how it occurred. Fundamen- 
tal information on deterioration processes not only 
was desirable in order to develop new and more effec- 
tive preventive treatments, but it could be applied in 
the development of more refined techniques for evalu- 
ating the suitability of materials for use in the tropics. 

Plans were initiated for a science mission to Pacific 
areas with the following objectives. 

1. To determine the causes of tropical deterioration 
with emphasis on determining the role play^ed by 
microorganisms (molds and bacteria). 

2. To determine the mechanism by which the dam- 
age is done, including the sequence of the changes 
where more than one organism is involved. 

3. To determine the effectiveness of the fungicides 
at present in use. 


4. To test under field conditions new fungicides 
selected because of their promise under laboratory 
conditions. This work would not merely serve to eval- 
uate the new fungicides but would provide a valuable 
correlation of laboratory tests with similar tests under 
actual operating conditions. 

5. To collect and bring back : 

a. Pepresentative samples of materials showing 
tropical deterioration. 

h. Cultures, isolated in the field, of biologically 
active agents in deterioration. 

c. Any samples of enemy equipment which show 
superior resistance to tropical deterioration. 

6. To contact the Australian laboratories, field sta- 
tions, and other agencies making such investigations 
in that area and report on the work which they are 
doing relative to tropical deterioration. 

After final arrangements for departure were made, 
it was necessary to cancel these plans. It was arranged, 
however, for a modified program to l)e undertaken in 
Panama. This consisted primarily of the studies on 
the deterioration of textiles as summarized in Chap- 
ter 4. These Panama studies contributed to a clear 
understanding of the deterioration process as it af- 
fects textiles, and furnished valuable information with 
respect to the nature and action of the biological 
agents of deterioration. Had it been possible to con- 
duct these studies in the Pacific, the results would 
have had even fuller significance. Not infrequently, 
as the TDAC program developed, important ques- 
tions were raised which could have been properly an- 
swered if there had been available full knowledge of 
field conditions or how protective treatments of items 
of equipment performed in the field. There have been 
many indications that the program of tropical dete- 
rioration in this country would have benefited exten- 
sively had the proposed mission to the Pacific been 
allowed to carry on its program. 




Chapter 2 

ORGANISMS ASSOCIATED WITH TROPICAL DETERIORATION 


2.1 INTRODUCTION 

I NTEREST AND ATTENTION was directed to the rela- 
tionship of fungi to the tropical deterioration of 
materials because fungi were conspicuous on dete- 
riorated materials in the tropics and knowledge of 
their characteristics and properties led to the obvious 
conclusion that they were the causal agents of many 
forms of deterioration. Australian studies in New 
Guinea early in World War II emphasized the pre- 
dominance and importance of fungi in the deteriora- 
tion of many types of stores. 

Fungi are found growing in nature under a wide 
variety of conditions and their reproductive structures 
or spores are universally distributed. The soil contains 
enormous populations of fungi. These soil-inhabiting 
forms develop airborne spores which inoculate mate- 
rials, and under proper conditions of moisture and 
temperature such spores are capable of germination 
and growth. The majority of fungi which have been 
shown to be significant in the deterioration of mate- 
rials are characteristically soil-inhabiting forms. 

Fungi, as well as bacteria, in contrast to green 
plants, comprise a group of organisms which are un- 
able to synthesize the energy yielding organic com- 
pounds necessary for their metabolic activities, except 
for relatively few exceptions, and consequently these 
compounds must be derived from external sources. 
By means of enzymes secreted by the organisms, elab- 
orate and insoluble organic substances can be broken 
down to simple and soluble materials capable of ab- 
sorption. The different species of fungi and bacteria 
vary in the limits within which they are able to attack 
organic substrates, but collectively they can effectively 
decompose most organic materials. It is by such ac- 
tivity that these organisms deteriorate many mate- 
rials; in many cases, however, the mere presence of 
the organisms is undesirable. 

For detailed considerations of the structure and 
physiology of various fungi and bacteria reference can 
be made to the many textbooks and treatises on the 
subject. Selected references are given in OSRD Re- 
port 6267' issued by the Tropical Deterioration Ad- 
ministrative Committee [TDAC]. Many reports pre- 
pared on the subject of tropical deterioration have 
given only cursory treatment to the organisms con- 


cerned. The report cited above considers the nature 
and characteristics of some fungi associated with trop- 
ical deterioration in slightly greater detail, and was 
prepared primarily for the use of Army and Navy 
laboratories engaged in studies on tropical deteriora- 
tion. 

Fungi are encountered as deteriorative agents in 
temperate regions as evidenced by molding of food- 
stuffs, leather goods, and such items as shower cur- 
tains, wood, and paint ; but, except for the l ather wide- 
spread damage to crop plants, they are of relatively 
minor economic significance. With the importance 
which fungi assumed in tropical deterioration it was 
necessary to determine whether the tropical forms em- 
braced types different from the more commonly known 
temperate forms, and if they were the same, whether 
the tropical forms represented different or more potent 
physiological strains. As a result of the work under- 
taken, comparative evaluations can be made and these 
are discussed in Section 2.2.7. The importance of es- 
tablishing these points is obvious when it is considered 
that preventive measures can be applied more intel- 
ligently when the exact nature of all deteriorating 
factors is known. 

Prior to the work of TDAC, the significance of 
bacteria in the deterioration of materials in the tropics 
was genei*ally disregarded, or if acknowledged, was 
deemed to be relatively unimportant, except in the 
destruction of foodstuffs. In the TDAC program, pro- 
vision was made for field studies on the role of bacteria 
in the deterioration of fabrics. These were found to 
play an important role which is discussed in Sections 
2.3 and 4.5. 

The only investigations concerning insects and other 
forms of animal life as agents of deterioration were 
those relative to the part played by mites in the de- 
terioration of optical instruments as discussed in 
Chapter 3. 

2 2 TROPICAL FUNGUS CULTURE 
COLLECTION 

Procedures essential to proper care and mainte- 
nance of fungus cultures for intensive study and 
preservation are such that permanent and well 


7 


8 


ORGANISMS ASSOCIATED WITH TROPICAL DETERIORATION 


equipped laboratory facilities are necessary. The Trop- 
ical Fungus Culture Collection [TFCC] was estab- 
lished by TDA(^ at the Biological Laboratories of 
Harvard University to serve as a place for deposit 
and maintenance of fungus cultures isolated during 
held studies of tropical deterioration. In addition to 
this phase of its activity, TFCC distributed cultures 
on hand to laboratories of the Army and Navy and 
other authorized agencies for study or for use as test 
organisms. 

The following discussion pertaining to TFCC is 
based upon OSIH) lieport r568r“ which summarizes 
the studies which were conducted. 

2.2.1 Purpose of the Tropical Fungus 
Culture Collection 

The field studies from which the majority of fungus 
cultures in the collection were obtained pertained to 
the deterioration of textiles and these are described 
in Chapter 4. With reference to these field studies it 
was intended that the functions of TFCC would be 
to isolate when necessary, to purify, to identify, and 
to preserve the fungus cultures related to fabric de- 
terioration. The desirability of having fungi of known 
potentiality generally available for use as test organ- 
isms was recognized, and it was also intended that 
TFCC would serve as a distribution center for all 
such cultures which were available. 

The phase of the program concerned with the organ- 
isms isolated during field studies of textiles paralleled 
studies by Quartermaster laboratories which involved 
determining the organisms responsible for the dete- 
rioration of textile fabrics (sec Section 4.8). One point 
in contrast, however, is that the cultures which were 
the subject of the Quartermaster investigations were 
isolated from materials returned from tropical areas 
and isolation was made in this country. Because of 
the relationship and importance to the Quarterma.ster 
program, close cooperation with Quartermaster pei’- 
sonnel was maintained throughout the period of 
activity. 

The task of purifying, identifying, and particularly 
maintaining and preserving the fungus cultures was 
one of immense proportions. The very nature of the 
ultimate objectives of all phases of the study made it 
desirable to have as much information as possible on 
the physiological characteristics of the organisms in 
order to determine with some exactness the role of the 
organisms in the deterioration of the test fabrics. 


Much of this information could be derived from exist- 
ijig knowledge of the organisms once identification 
was made. Accordingly, studies concerning the iden- 
tification of the fungi Avere given first priority. A^alu- 
able supplementary information on the properties of 
many organisms involved in tropical deterioration Avas 
derived from physiological studies by the Australian 
Mycological Panel and laboratories of the De])artment 
of Agriculture and those of other TDxAC contractors. 

The Avork of TFCC Avas of such magnitude that it 
could not be completed by TDAC and it Avas arranged 
that this project Avould be continued by the Office of 
the Quartermaster General. The collection has con- 
tinued to occupy aji important position in the Quarter- 
master program concerning textile deterioration. 

2.2.2 Organisms in the Collection 

The cultures deposited in the collection totaled 
4,103; most of these came from the Canal Zone, some 
from subtropical United States, and a fcAV from Aus- 
tralia. The nature of the cultures and their sources 
are indicated beloAv. 

Cultures from Australia 

These comprised a small set of 40 cultures furnished 
by the Mycological Panel of the Scientific Liaison 
Bureau, Australia, and Avere derived from their ex- 
tensive collection isolated from deteriorated materials, 
chiefly from NeAV Guinea, in the course of field AA^ork. 
These cultures included fungi Avhich Avere destructive 
to cellulose and other basic materials as AA-ell as to 
various components of the finishes of textiles and 
sleeving and insulation of Avires. Through intensiA^e 
study by the Mycological Panel, the potentialities of 
these cultures AA^ere determined as Avell as their ap- 
plicability to tests for evaluating the tropic-proofing 
of a Avide variety of items. 

Cultures from Quartermaster Cot.lection 
IN Florida 

This set of 1,517 cultures of microorganisms Avas 
derived from deteriorated articles AAdiich AA^ere repre- 
sentative items of equipment exposed in storage dumps 
under conditions carefully planned to approximate as 
closely as possible those AAdiich had been found to 
prevail under actual operations in the Pacific. The 
entire range of conditions encountered Avas represented 
in the indiAudual dumps. Fluctuations of tempera- 
tui’e and moisture AA'ere recorded, the conditions of the 



TROPICAL FUNGUS CULTURE COLLECTION 


9 


various representative items of equipment were ob- 
served, the progress of the deterioration of various 
articles was noted and from them the molds and other 
microorganisms were isolated at suitable intervals as 
the exposure progressed. The purpose of this collection 
was primarily to gain information as to the identity 
and significance of the organisms concerned in the 
deterioration of materiel under field conditions in the 
subtropical United States where the rigors of climate, 
to a milder degree, approximate those of the tropics. 

Cultures from Panama 

Textile Exposure. These organisms were derived 
from the exposure of three sets of experimental tex- 
tiles. A large majority of the organisms were obtained 
from the textile exposures described in Chapter 4 
which were performed at Barro Colorado Island, 
Panama. Of the various methods which were used to 
isolate fungi from these textile samples, the method 
in which bits of yarn from obviously affected spots 
were teased out under aseptic conditions was most 
widely used. This method was found especially helpful 
in revealing the fungi which were actually growing 
in the fabric, thus causing its deterioration, and dis- 
tinguished them from the fungi which were super- 
ficial or adventitious on the fabric. In all, about 2,000 
cultures were isolated in the course of this work and 
approximately 75 per cent of them were identified 
by October 31, 1945. 

In another of the textile exposures using the same 
materials of the initial test, the exposure plan was 
modified in order to provide more realistic conditions 
which more closely approximated field use of textiles. 
When last reported, oidy about 200 cultures of fungi 
were received from this test, but when the entire com- 
plement is obtained, they should present a highly 
significant comparison with the original textile ex- 
posure test since the samples are exact duplicates. 
The difference in weather conditions and the difference 
in exposure, in that periods of exposure were alternated 
with periods of storage, should give some evidence as 
to the influence of these additional factors on the de- 
teilorating action of the fungi conceriied. 

The other textile exposure test from which fungi 
were isolated was also performed under Quartermaster 
auspices. The exposure was planned to secure evidence 
on the influence of the various light-screening com- 
pounds, finishes, and fungicides on deterioration. For 
this an entirely new set of fabrics was prepared and 


included those which had only preparatory and dye- 
ing treatments with no fungicide, those treated with 
light-screening compounds with or without selected 
fungicides in various combinations after preliminary 
treatment, and those treated with selected fungicides 
after preliminary treatment. The exposure was varied 
according to the treatments which were given to the 
samples. By the end of October 1945 only about 100 
cultures of fungi from the samples were received. The 
identification of fungi from these samples is to be 
correlated with investigations on the chemical aiid 
photochemical degradation of the samples and, when 
this information is complete, it should contribute ma- 
terially to an understanding of the influence and com- 
plicated interaction of the molds, the fabric, the finish, 
and the climate in relation to tropical deterioration. 

Sterilized Cotton. A large number of cultures were 
derived from cotton fabrics which were exposed after 
sterilization by steam under pressure or by the use of 
disinfectants such as formaldehyde or ethyl alcohol. 
The purpose of these exposures was to gain evidence 
as to the identity and the time of development on the 
sterilized fabrics of mold derived from natural sources 
in the vicinity. An analysis of these organisms should 
shed some light on the influence of such sterilization 
methods on the subsequent development of molds on 
the samples. By comparison of these fungi with those 
isolated from comparable unsterilized samples, in- 
formation relative to the influence of spores picked 
up in manufacture or transit to the tropics should 
l)e clarified. 

Natural Molds. These cultures were collected with 
the purpose of determining the natural sources of 
fungi which had been found to be most predominant, 
frequent, or significant on the exposed textiles. 

Ctdtures from Optical Instruments and Miscellane- 
ous Materials Exposed. A total of 291 cultures were 
obtained from optical instruments and materials other 
than textiles which were exposed at Barro Colorado 
Island for TDAC. 

Cultures from Miscellaneous Sources 

In addition to the more extensive and important 
sets of cultures indicated above, there were received a 
number of miscellaneous acquisitions mostly in rather 
small lots sent either for identification, comparison, 
or study. Most of them were submitted by laboratories 
of the Army or Navy or of other government agencies. 


10 


ORGANISMS ASSOCIATED WITH TROPICAL DETERIORATION 


^ Cultures Distributed 

A total of 1,352 cultures were sent out from the 
Tree during the first 14 months of its existence. 
These cultures fell into three main categories; (1) 
Identified cultures of known potentialities sent to 
authorized agencies chiefly for use in testing, (2) pre- 
liminarily identified cultures sent to specialists in the 
taxonomy of notoriously difficult genera for final spe- 
cific identification, and (3) cultures removed for per- 
manent inclusion in other collections, particularly 
bacteria and yeasts. 

The cultures for use in testing were supplied pri- 
marily to laboratories of the Army or Navy and were 
largely those from the Australian Mycological Panel 
because of their known potentialities and applicability 
for testing purposes or because of their value as stand- 
ards of comparison for species in process of identifica- 
tion. In most cases only a few of these cultures were 
sent to the requesting laboratory, but in four instances 
the entire set was requested and sent. In one instance 
a selection of four cultures specified in connection 
with tests on coating materials and hookup wires was 
made available to the American Type Culture Col- 
lection to serve as a source of supply for industrial 
laboratories. 

The cultures which were sent to specialists for final 
identification were primarily those of the genera As- 
pergillus and Penicillium and their allies, Fusarium 
and its relatives, or Mucor and related forms. The 
practice of referring species of these difficult genera 
to experts for identification was followed in order to 
expedite this phase of the work. 

The bacteria cultures were transferred to the TDAC 
Bacteria Culture Collection (see Section 2.3) and the 
yeast cultures were sent to the University of Califor- 
nia where studies on yeasts were being conducted for 
the Office of the Quartermaster General. 

2 2 Isolation and Purification 

or Separation of Cultures 

The cultures isolated in the course of field studies 
were supposedly pure, that is, they contained only one 
organism. However, for the most part they had been 
isolated only recently in field laboratories under dif- 
ficult conditions and in most cases had been trans- 
ferred only once from the original petri dish cultures 
in which bits of yarn or other suitable inoculum had 
been placed. As a result, a considerable portion of 


these, in some lots over 60 per cent, proved to be mix- 
tures. Hence, considerable time and effort were re- 
quired for separating these mixtures into the two or 
more individual cultures which were represented. Such 
problems as these are ordinarily encountered even 
under the most suitable conditions and it was realized 
that such culturing and reculturing of the field mate- 
rial would be an essential part of the work, and it was 
for this reason that the TFCC was regarded as a neces- 
sary corollary to successful field studies. 

Certain of the mixtures encountered gave particular 
difficulty in separation. One of these was a mixture of 
slowly growing, nonsporulating mycelium with a rap- 
idly developing, abundantly sporulating contaminant 
such as Fusarium, Mucor, or Trichoderma. Mixtures 
of two nonsporulating mycelia of approximately simi- 
lar growth rates and superficial appearance also ap- 
peared to be very troublesome. To separate such mix- 
tures as these required repeated attempts in which a 
wide variety of specialized isolation procedures were 
employed. 

Contamination with various mites was also experi- 
enced to a considerable extent in some lots of the cul- 
tures received. Mite contamination is undesirable par- 
ticularly in that it superimposes an added difficulty 
in obtaining pure cultures. To prevent the spread of 
mites and disastrous infestation of other cultures on 
hand, the use of mineral oil to cover the actively grow- 
ing cultures proved highly successful. 

As a result of this subculturing of the cultures 
which were received, the number of individual fungi 
in the collection was increased. Whereas the cultures 
received totaled 4,103, the others separated later in 
the purification of the mixed cultures would increase 
the actual number of different fungi to around 4,500. 


2.2.5 Maintenance of Cultures 

The fungi deposited in the TFCC were maintained 
both in the active growing state and also preserved for 
long-time survival in a dormant inactivated condition. 
It was necessary to maintain active growing cultures 
for purposes of distribution to other laboratories as 
well as for use in identification of the organisms. The 
program on long-time preservation of the cultures was 
undertaken in order to lessen the task of maintaining 
all cultures in a viable condition and to conserve for 
future study this highly important and significant 
collection of tropical fungi. 


TROPICAL FUNGUS CULTURE COLLECTION 


11 


Maintenance of Cultures in the Active State 

Potato-maltose agar of the following formulation 
was used to maintain active growing stock cultures: 
300 g potato, 10 g maltx)se, 20 g agar, 1 1 water. This 
proved to be most successful for a wide range of dif- 
ferent fungi, both for securing abundant sporulation 
and for supporting long continuing normal growth. 
For comparing the colony growth, color production, 
and other characteristics essential for identification, 
the standard comparison media of different formula- 
tions were used as recommended by the experts in the 
various taxonomic groups represented. It was also nec- 
essary to use special culture media for growing those 
fungi which proved to be very slow in developing diag- 
nostic characteristics, including nonsporulating my- 
celia. Special culture procedures were also employed 
in securing critical developmental stages for proper 
identification of many of the forms. 

Maintenance of Inactivated Cultures — 
Lyophilization 

Inactivation of fungi by this method involves the 
use of a small amount (.05 cc) of a dense suspension 
of spores in some lyophilic colloid such as horse serum 
or skim milk. This suspension is placed in small con- 
tainers, such as Pyrex glass tubing (7 mm OD), and 
is instantly frozen at a low temperature ( — 50 to — 60 
C). After freezing the spore suspension is dried by 
pumping off the water vapor by sublimation under a 
vacuum of about 100 /x of mercury nntil a dry pellet 
is obtained. The glass tubing is then fused off and the 
container with the pellet is hermetically sealed. 

This method had originally been used for the in- 
activation of bacterial cultures and had proved highly 
successful except in the case of certain notably sensi- 
tive and vulnerable forms. Eecently the procedure has 
been successfully applied to the conservation of se- 
lected cultures of yeast. A small apparatus had been 
constructed by the Harvard Laboratory for preserving 
the collection of fungi previously present there. Mean- 
while, extensive experiments had been conducted at the 
Northern Regional Research Laboratory in which this 
method was applied to the preservation of numerous 
fungus cultures, particularly species of Penicillium. 
A copy of a manuscript in the process of publication, 
which appeared in the July- August 1945 issue of My- 
cologia, describing the results of this experimentation 
was loaned to the culture collection, and this proved 
to be very useful and advantageous to the program. 

The lyophil method of long-time preservation of 


fungi can be applied to a wide variety of forms but 
not to all. Technical difficulties as well as the failure 
of certain types of spores to withstand the relatively 
drastic method of treatment prevented this method 
from being used for all organisms represented in the 
collection. Nevertheless, in addition to the fact that 
the lyophilization program provided a means whereby 
these cultures could be preserved for intensive study 
at a later date, it saved considerable expense and en- 
ergy by reducing the maintenance program and allow- 
ing, as a result, more time for the critical task of 
identifying the cultures at liand. By October 31, 1945, 
a total of 1,734 cultures was preserved by lyophiliza- 
tion, and the program was continuing at the rate of 
around 300 cultures per month, mostly in triplicate. 

Maintenance of Inactivated Cultures — 
Inactivation under Mineral Oil 

By this method, young vigorous colonies growing 
in ordinary 6-in. test tubes on agar medium are con- 
served by pouring in sterile mineral oil until the 
tip of the agar slant is submerged about 1 to IV 2 cm 
below the surface of the oil. This layer of mineral oil 
cuts down evaporation and slows down the activities 
of the colony so markedly that, if kept in a refriger- 
ator or even in a cool room temperature, the cultures, 
while they may show some growth, will retain their 
viability for as long as two, three, or even more years. 

This method also had originally been used for the 
conservation of bacterial cultures. Reports had also 
been made on the successful application of this pres- 
ervation method to fungi for periods of at least 18 
months. The advantages and disadvantages of this 
method of conservation of fungi are discussed in 
OSRD Report 5681^ and they are based on the broad 
experience gained during the activity of the collec- 
tion. In general, it was felt that the advantages far 
outweighed the disadvantages in using this technique. 
Many factors in its favor are cited in addition to the 
one cited previously concerning the control of mites 
which may be present in the cultures. 

As with the lyophilization program, this program 
involving the conservation of cultures by the use of 
mineral oil represents the first instance in which this 
method was applied to such a large number of cul- 
tures of such diversified types. In all 756 cultures were 
thus conserved by October 31, 1945. Therefore, the 
cultures which were conserved by both the use of 
mineral oil and lyophilization represented approxi- 
mately two-thirds of those present in the collection. 


12 


ORGANISMS ASSOCIATED WITH TROPICAL DETERIORATION 


" Study and Identification 

For the most part, the study of the fungi present 
in the collection was confined to that which was essen- 
tial for their identification. A considerable amount of 
study was devoted to developing or modifying methods 
to facilitate, expedite, and improve the procedures 
necessary for the preparation of such large quantities 
of material for identification. For reference purposes, 
record was made of critical or important fungi by re- 
taining them as dried herbarium specimens or by 
preparing Kodachrome photographs for accurate 
permanent records to show the color and growth 
characteristics of colonies grown in petri dish cultures 
on standard comparison media. 

The most significant and essential activity in con- 
nection with the study and identification of the fungi 
was the preparation of permanent microscopic slides 
which served not only as a basis for identification but 
continued to serve as essential reference material for 
subsequent comparison and identification. This slide 
collection in itself constitutes a valuable and indis- 
pensable record of the fungi. 

A total of 3,821 such slides was prepared by Oc- 
tober 31, 1945. Their preparation, in many cases, 
involved various specialized techniques directed to 
secure and prepare the critical material necessary for 
identification. The various techniques employed and 
the use of a new material which was adopted for seal- 
ing cover glass mounts are described in a report issued 
by TDAC, DSHD 5681.^ 

The majority of the determinations and identifica- 
tions were made by the expert personnel of Harvard 
University associated with the contract. Of the 1,032 
cultures which were sent to specialists for identifica- 
tion, as indicated in Section 2.2.3, identifications of 368 
were completed and returned l)y the end of October 
1945. By this date a total of 2,275 identifications had 
been made. More than two-thirds of the identified 
cultures were isolated in the Panama Canal Zone. The 
appendix of OSRD Report 5681^ lists in alphabetical 
order by genera and species these identifications. 

^ Conclusions — Points of Interest 

Instances of Association and Interaction 
BETWEEN Fungi 

Certain stubborn associations of organisms have 
been encountered repeatedly and these have required 
considerable skill and patience to separate into pure 


cultures. The frequency of occurrence, the compati- 
bility, and stubborness of these associations suggest 
that they may l)e advantageous rather than merely 
chance combinations among the mixed populations 
common under natural conditions. These associations, 
as indicated and discussed in ()8hM) Report 5681,- in- 
volve species of Trichoderma and Botryodiplodia, 
Trichoderma and Fusarium, Pullularia and Penicil- 
lium, Botryodiplodia and Mucor, Fusarium and Mu- 
cor, and Fusarium and Pestalotia. Another such asso- 
ciation frequently encountered was the mixture of a 
small yellow rod-form bacterium with Pullularia or 
with the two Phycomycetes, Blakeslea and ('hoane- 
phora. Two instances of parasitic association of fungi 
were encountered. One involved a Septonema-like im- 
perfect fungus parasitic on and in the mycelial fila- 
ment of the Phycomycete mold, Zygorhyncus. The 
Septonema was finally isolated from the Zygorhyncus 
through its rapid growth on such cellulose containing 
substrata as mineral salt solution plus fdter paper, on 
which the Zygorhyncus developed oidy meagerly. The 
other involved a very delicate slender filamentous or- 
ganism so inconspicuously parasitic in a Stachyl)otrys 
culture from Australia that it escaped notice for 
months but when discovered was traced through all 
successive transfers back to the original culture tube. 
By use of this same culture medium these two organ- 
isms were separated; interestingly enough, the para- 
sitic organisms which had Actinomycete-like charac- 
teristics outgrew the reputedly cellulose-preferring 
Stachybotrys. It was noted that although the collec- 
tion contained a number of cultures of renicilliani 
rugulosum, well known for its frequently and usually 
destructive parasitism on species of Aspergillus, espe- 
cially A. niger, all of the cultures were isolated not as 
parasites on molds but as saprophytes on textiles and 
other exposed materials. 

Among the instances of interaction between fungi 
which were noted in the course of the work was one 
of particular interest because it involved the stimula- 
tive action of substances produced by one mold on the 
sporulation of others which had previously produced 
spores in only meager amounts. This proved to he of 
practical value because adequate spore loads for lyo- 
philization were thus secured. Cultures of Blakeslea 
are difficult to maintain because they sporulate only 
rarely and sparsely and those present in the collection 
were no exception. Chance contamination in petri 
dish cultures of Blakeslea were observed to stimulate 
spore production. In further experimentation, crude 
sterile filti'ates from the growth of the contaminant 


TROPICAL FUNGUS CULTURE COLLECTION 


13 


Penicillium on liquid media were added to various 
nutrient agars and produced abundant sporulation by 
this species of Blakeslea. Further investigation may 
reveal the nature and mechanism of this stimulation. 

Problems Presented by Nonsporulatixg Mycelia 

Because of the disproportionate amount of labor 
involved in obtaining sporulating cultures of these or- 
ganisms, identification has not been made other than 
to assign them to major groups of fungi when possible. 
The lyophil technique cannot be applied to these and 
all of them have been conserved under mineral oil for 
study at a later date. Many of them apparently play 
an active part in deterioration, especially in the deg- 
radation of cellulose. They are common in nature and 
number 330 cultures or about 8 per cent of the total 
number in the collection. Separation of these organ- 
isms from contaminants and their maintenance in 
active culture present numerous problems and diffi- 
culties but these have been lessened considerably by 
using the mineral oil conservation technique. 

Frequexcy of Bepresextation 

As OSBD Report 5681^ points out, attempts to use 
the frequency of representation of fungi in collections 
as a basis for conclusions as to their signficance in 
deterioration must be made with due consideration of 
the factors involved. Ordinarily, it would be concluded 
that those forms represented most frequently would 
be those organisms most concerned in any deteriora- 
tion process. However, there are many interacting 
factors which must be taken into consideration in 
evaluating the significance of such frequencies. Such 
factors as the geographic locality, the seasons, the 
nature of the article from which the organism has 
been isolated, the exposure given to the article, and 
the method and medium used in making the isolation 
are important and must be evaluated accordingly. 

In the case of the original textile exposures in 
Panama adequate information on many of these inter- 
acting factors has been secured and some sound pre- 
liminary conclusions have already been presented in 
OSRD Report No. 4807^ issued by TDAC. However, 
further detailed analysis remains in evaluating the 
significance of the occurrence of the various fungi, 
particularly comparison with exposure tests conducted 
later as indicated in Section 4.4.7. At the date of the 
last report, a total of 1,330 identifications of fungi iso- 
lated from the original textilQ exposure had been 


made; this represented practically the entire series 
of cultures. 

The frequency of representation in this 1944 series 
is of interest. The genera most frequently represented 
are Penicillium with 195 cultures out of the total 
1,330, Aspergillus with 56, Fusarium with 156, 
Trichoderma with 145, Pestalotia with 106, Pullularia 
with 100, and Botryodiplodia with 78, these seven com- 
prising 836 cultures, or 63 per cent of the total. In 
contrast certain common and very widespread genera 
show notably meager representation, Phoma compris- 
ing only 18 cultures, Cladosporium 11, Alternaria 3, 
Rhizopus 7, and Syncephalastrum 1. Certain other 
genera, now well known in the deterioration program 
because of their destruction of cellulose, are sparsely 
represented, Curvularia comprising 9 cultures, Brachy- 
sporium 7, Metarrhizium 2, Memnoniella 1, while 
neither Stachybotrys nor Chaetomium appear at all ! 
The troublesome, yet important, group of the non- 
sporulating mycelia is not of course truly comparable 
to a genus since it is a heterogeneous, inclusive, mis- 
cellaneous assemblage of greater scope, yet for pur- 
poses of comparative analysis it is notable that these 
comprise 185 isolations, about 15 per cent of the total 
in this series and almost double the 8 per cent repre- 
sentation in our whole collection. Certain species show 
notable frequency, Trichoderma viride being repre- 
sented by 134 cultures, Penicillium citrinum by 101, 
Pullularia pullulans by 95, Botryodiplodia theohromae 
by 76, Penicillium westlingi by 23, Aspergillus versi- 
color by 22, and Pestalotia virgatula by 14, these seven 
species including 465 isolations or 37 per cent of the 
total 1,330. 

In contrast a relatively large number of species, 
some of them common and widespread, are represented 
only once in this 1944 series. Among these are 9 spe- 
cies of Penicillium, several of which are of common 
occurrence, 7 species of Aspergillus, most of which are 
common and widespread, and 5 species of Fusarium, 
all of which are widely distributed components of the 
soil flora. Mucor genevensis, here represented once, is 
of very common and widespread occurrence in soil; 
Memnoniella echinata is common on plant remains 
throughout the tropics, as is Pestalotia royenae. 

It is noteworthy that the classic test fungi which 
have been accepted as standard organisms for accept- 
ance and performance testing are certainly not fre- 
quent in this series. Chaetomium glohosum does not 
occur at all in this set although in the culture collection 
as a whole it is represented by three cultures in other 
Canal Zone sets and by six from the Florida five 


14 


ORGANISMS ASSOCIATED WITH TROPICAL DETERIORATION 


months’ storage exposure test. Meiarrhizium glutino- 
siim is represented only twice in this series and occurs 
twice in the Florida sets. Memnoniella ecJiinata is rep- 
resented but once in this set in contrast to twice in 
other Canal Zone collections and four times in the 
Australian Mycological Panel set. Stach gbotrys atra 
is not represented in this series although occurring in 
six cultures in the remainder of the collection. Asper- 
gillus flavus is represented once versus ten times in 
the remainder of the collection, Aspergillus niger three 
times versus 23 in the remainder, PenicilUum luteurn 
twice versus seven; Trichoderma viride, however, is 
extremely frequent. It should be noted, however, that 
some of the cultures comprised in this inclusive identi- 
fication are not of the type suitable for testing since 
they do not bi'eak down cellulose. 

Certain general conclusions are drawn in OSPD 
Report 5681 with reference to the natural sources of 
the organisms which seem to be most concerned with 
deterioration in the Canal Zone. 

Such species as Trichoderma viride, Botrijodiplodia 
ilieohromae, and Pesfalolia I'irgalula are shown in sup- 
plementary collections from the Canal Zone to be com- 
mon in the vicinity on decaying vegetation and to be 
carried to the exposed textiles by air currents and by 
splashing, dripping, or wind-borne rain. Pullularia 
pullulans and the frequently represented species of 
Penicillium, Aspergillus, and Fusarium are common 
in the soil and readily transported in dust or spattered 
particles. Once lodged on the textiles the several most 
frequently represented fungi became predominant and 
were consistently predominant in all successive peri- 
odic isolations throughout the ten months’ duration of 
exposure. On the other hand the rarity of Cunning- 
hamella, with one isolation, in contrast to the com- 
parative frequency of its close relatives, Blakeslea with 
21 isolations and Choanephora with 18 isolations, is 
puzzling. All three are common in the vicinity and 
none of them use cellulose as a carbon source. Since 
Blakeslea and Choanephora occur naturally on flowers 
and succulent fruits while Cunninghamella commonly 
develops on such substrata as dung of herbivorous 
animals or on nuts rich in nitrogenous materials, 
it is possible that the relative absence of nitrogen 
sources in the textiles is responsible for the scarcity 
of Cunninghamella. 

COMPAIUSOX WITH SlMILAU COLLECTIONS FROM 

OTHER Regions 

Comparison of the organisms isolated from the orig- 
inal textile exposure test with a few available lists of 


fungi from other localities brings up certain points of 
interest. 

Only 280 cultures have been identified from the 
Quartermaster Florida storage deterioration tests. The 
distribution of these in the principal taxonomic groups 
of fungi agrees rather closely with the taxonomic dis- 
tribution of the fungi from the original textile expo- 
sure series. The genera Penicillium, Aspergillus, and 
Fusarium show the highest frequency of appearance 
in both the original textile exposure series and in the 
Florida storage deterioration tests. However, the gen- 
era Trichoderma, I’ullularia, Pestalotia, and Botryo- 
diplodia are represented far more frequently among 
the organisms from Panama than among those from 
Florida. However, Cdiaetomium and Stachybotrys are 
represented in the Florida collection more frequently 
than they are in the Panama collection. Cunningham- 
ella is meagerly represented in both collections but 
the closely related genera, Choanephora and Blakeslea, 
which both occur in the Panama isolations are absent 
from the Florida collection even though they are both 
known to exist in that region. 

A rough comparison of the Panama fungi with 
fungi isolated from deteriorated materials returned 
from Pacific areas can be obtained by contrasting the 
occurrence of the nine most frequent species in the 
Pacific list with the occurrence of the same species in 
the Panama list. From 1,000 isolations performed 
from 137 samples of deteriorated materials, a prelimi- 
nary list of 658 identified organisms was kindly fur- 
nished by the Tropical Deterioration Research Labo- 
ratories at the Philadelphia Quartermaster Depot 
which performed this investigation. 

The following list compares these nine most fre- 
quent species among the Pacific fungi with their fre- 
quency in the Panama isolations; representation of 
the genera Pestalotia, Chaetomium, and Fusarium is 
also included. 

Pacific Series Panama Series 


Aspergillus niger 

45 

3 

M emnoniella echinata 

35 

1 

Aspergillus flavus 

29 

1 

Aspergillus sydowi 

24 

2 

Penicillium biourgeianu m 

17 

0 

Aspergillus terreus 

16 

0 

Trichoderma viride 

16 

134 

Botryodiplodia theobromae 

12 

76 

Pullularia pullulans 

10 

95 

Pestalotia 

4 

106 

Chaetomium 

39 

0 

Fusarium 

43 

156 


OSRD Report 5681^ compares the cultures from 
Panama with those reported as being important in 


BACTERIA CULTURE COLLECTION 


15 


tentage and cordage deterioration in India.® In this 
report 74 species are listed. In general the fungi of 
this list closely parallel those from the Panama textile 
exposure, but there are certain striking discrepancies 
between the two lists. The organisms most frequently 
isolated in India during different seasons are either 
absent or only meagerly represented in the Panama 
collection. The only exception is in the case of species 
of Fusarium which were isolated abundantly from both 
regions. The differences may possibly be accounted 
for by the fact that different culture methods were 
used in the isolation of the organisms. 

It will remain for future detailed analyses involv- 
ing precise comparative studies to evaluate the signi- 
ficance of agreement or disagreement in the frequen- 
cies of organisms isolated from different regions, such 
as have been discussed above. 

General Significance of the Fungi 

Examination of the list of fungi from the Panama 
textile exposure test, with the assumption that they con- 
stitute a representative cross section of the mycological 
flora concerned in the deterioration of cotton fabrics in 
the Canal Zone, does not reveal a specialized individual 
flora distinctive or restrictive with respect to locality, 
sources, substrata, or activity. The primary source of 
the organisms is from the complicated flora of the soil 
while a secondary source is from the more restricted 
flora of decaying plant remains. Practically all the 
organisms are included in published works. Many of 
the fungi are not restricted to the Canal Zone and are 
widely distributed in subtropical and temperate re- 
gions. The organisms are a conglomerate, heterogene- 
ous assemblage including forms which are well known 
in connection with the spoilage of food and pharma- 
ceutical products, plant diseases, human diseases, such 
as ear and skin infections, and sources of antibiotic 
substances of potential therapeutic value. This is only 
a brief survey but it does indicate that those fungi 
which have been assembled in tropical deterioration 
studies have broad significance and represent interest- 
ing scientific possibilities and exploitable practical 
potentialities. 

New Genera and New Species 

In addition to the known fungi which comprise the 
bulk of the organisms present in this collection, there 
have been encountered representatives of eight dif- 
ferent genera and fifteen different species which were 


previously unknown. Practically all of these were iso- 
lated in the course of the original textile exposure and 
when judged on the basis of the unusual frequency of 
new forms in collections, this constitutes an inordi- 
nately high percentage of new organisms. OSRD 
Report 5681 indicates the importance of the new 
forms to tropical deterioration and to the science 
of mycology. 

23 BACTERIA CULTURE COLLECTION 

The bacteria cultures which served as the nucleus of 
the Bacteria Culture Collection [BCC] were those iso- 
lated in field studies on the deterioration of textiles 
by the Panama Science Mission. The results of these 
field studies are given in OSRD Report 4806® issued 
by TDAC and these are briefly summarized in Sec- 
tion 4.5. 

It was not possible to identify fully the isolated 
bacteria in the field laboratories and all cultures were 
returned to this country pending decision to deter- 
mine the identity of the organisms. Two general 
classes of bacteria were isolated from deteriorated tents 
and tarpaulins in use and experimental test fabrics, 
these being bacteria capable of destroying cellulose 
and noncellulose-destroying bacteria. The importance 
of the cellulose-decomposing forms is obvious, and the 
noncellulose-decomposing forms were present on the 
fabrics in such large numbers that it seemed probable 
that they played an important part in the biological 
deterioration of the fabrics. 

The significance of these preliminary results was 
recognized and it was recommended by TDAC that 
the BCC be established for the purpose of identify- 
ing and preserving these cultures for future study. 
Accordingly, the collection was established at the 
Alabama Agricultural Experiment Station of the 
Alabama Polytechnic Institute with the cooperation 
of the Soil Conservation Service, U. S. Department 
of Agriculture. 

The identifications which had been made by October 
31, 1945 are summarized in the following section, 
based upon OSRD Report 5682.'^ 

2.3.1 Identification of Isolated Bacteria 

As with the TFCC, the enormous task of identify- 
ing the large numbers of bacteria which were depos- 
ited in the BCC could not be completed by TDAC. 
Bacteria isolations from the Panama field studies con- 


16 


ORGANISMS ASSOCIATED WITH TROPICAL DETERIORATION 


sisted of 400 odd cultures and their sources are indi- 
cated in Appendices 3 and 4 of OSRD 4806.® In addi- 
tion to these there were approximately 700 cultures 
deposited in the collection by Quartermaster labora- 
tories ; these were isolated from deteriorated materials 
returned from combat zones, mostly Pacific regions. 
Because of the interest and importance of knowing 
the identity of these bacteria to the program of the 
Office of the Quartermaster General, the contract un- 
der which the studies were conducted was continued 
by that office and the identification of the isolated bac- 
teria has been included among the research projects 
which have been given top priority in the Quarter- 
master program.® 

Identificatiox of Cellulose-Decomposixg 
Bacteria 

Eighteen of the 37 cellulose-decomposing bacteria 
isolated by the Philadelphia Quartermaster Labora- 
tory appear to belong to the Cytophaga group of bac- 
teria. It has been definitely determined that ten of 
these produce microcysts and except for one culture 
they all have been identified as Sporocijfopliaga rnijxo- 
coccoidcs. Further studies are necessary to determine 
whether the rest of these members of the Cytophaga 
group form microcysts as well as the identity of these 
cellidose-decomposing forms which do not belong to 
this group. 

All the 18 cultures of cellulose-decomposing 
bacteria from Panama have also been identified as 
l)elonging to the Cytophaga group. Most of these also 
a])pear to be l^povo cytophaga niy.vococcoides. Almost 
half of these cultures were isolated from fabric either 
in contact with the soil or buried in the soil, but the 
remainder were isolated from tentage and tarpaulins 
in use. It is perhaps significant that these cellulose- 
destroying forms occurred on those fabrics in use 
which were found to be most seriously deteriorated. 

The cellulose-decomposing bacteria in the collection 
which do not belong to the Cytophaga group have been 
less studied. They occur more widely than do the Cyto- 
])hagas and appear to resemble Cellulomonas bacteria. 

Identification of NToncellulose- Decomposing 
Bacteria 

Of the 260 cultures of noncellulose-decomposing 
bacteria from Panama about one-half have been found 


to be either yeasts or fungi. Many of these were found 
to be contaminated with a small rod-shaped bacterium, 
which was impossible to eliminate despite varied at- 
tempts to do so. This association was apparently very 
intimate because in none of the various cultures at- 
tempted did the bacterium form separate colonies. Of 
the 200 Panama cultures which are bacteria, about 
1/10 of them are cocci, small spherical organisms. 
The remaining cultures are practically all small rod- 
shaped forms; although separate studies of spore for- 
mation in the rod forms have not yet been made, cer- 
tain observations suggest that spore formers are less 
prevalent than would be expected from a considera- 
tion of the conditions under which the organisms ex- 
isted. The coccus forms were isolated from binocular 
lenses and leather stitching in addition to deteriorated 
fabrics, where they appeared to be more prevalent in 
advance stages of deterioration. 

No positive species identifications of the noncellu- 
lose bacteria cultures have been made. However, the 
organism Bacillus mycoides can be readily detected 
because of the characteristic growth hal)it on agar 
slants. On the basis of this characteristic this organ- 
ism makes up at least 8.5 per cent of the isolates made 
at the Philadelphia Quartermaster Laboratory and 
3.6 per cent of those made at the Jeffersonville Quar- 
termaster Depot, but it is not found in the Panama 
isolates. B. mycoides is widely distributed and its ab- 
sence from the Panama cultures is probably not due to 
differences in geographic location. It would seem to 
be more probable that since B. mycoides is a spore- 
forming organism, it either persisted during shipment 
of samples from the Pacific regions while less resistant 
organisms may have perished, or spores of the organ- 
ism may have been added to the samples in the process 
of handling and shipment. Other studies have shown 
that in soils B. mycoides occurs principally in the spore 
form and apparently is not active in microbiological 
changes which occur, and it may act similarly in the 
microbial complex found on deteriorating tentage. 

It should be pointed out that the identification of 
bacteria is a more laborious and time-consuming task 
than is the identification of most fungi. Because of the 
small size of these organisms, morphological character- 
istics are seldom critical in their identification, and 
recognition is based instead on physiological capacities 
or characteristics. Because of these reasons and because 
of the fact that necessary personnel to expedite the 
task of identifying the bacteria were unavailable, this 
task has not made as rapid progress as has the identi- 




lUlUflHUHHRRin 


BACTERIA CULTURE COLLECTION 


17 


fication of fungi. With this collection, an excellent 
beginning has been made toward obtaining a clearer 
understanding of the role which these organisms may 
play in the deterioration of fabrics under field condi- 
tions. Although the tentative evidence at hand indi- 
cates that they may play a significant, though minor 
role in fabric deterioration, the full story cannot be 
obtained until the organisms are identified, and their 
important physiological characteristics with reference 


to fabric deterioration determined. This research 
would include determining the ability or inability of 
the organism to attack the components commonly 
used in the finishing of fabrics, and even perhaps sup- 
plementing these studies with additional field studies 
particularly designed to approach critical aspects of 
the problem directly, rather than to make a general 
survey which is primarily concerned with determining 
the incidence of bacterial deterioration. 


Chapter 3 

PREVENTION OF DETERIORATION OF OPTICAL INSTRUMENTS 


31 INTRODUCTION 

R epokts from the United Kingdom, Australia, and 
the United States have stated that the problem 
of deterioration of optical instruments in the tropics 
is not a new one. It is indicated further in OSRD 
Report 6055^ issued by the Tropical Deterioration 
Administrative Committee [TDAC] tliat problems 
with optical instruments occurred during World War 
II largely because instruments designed and manu- 
factured for use in temperate zones were used in trop- 
ical areas. An Australian report" suggests that these 
}U’ol)lems assumed major importance because facilities 
for storage of instruments were extremely primitive 
in the early stages of the New Guinea campaign and 
because New Guinea is climatically one of the worst 
possible places for fungal trouble. In many localities, 
and certainly in the jungle itself, conditions of ex- 
tremely high humidity prevail throughout the whole 
year without the alleviation of a dry season such as 
occurs in some tropical areas. As a result, optical in- 
strument workshops, which were inadequately equipped 
and styled for even normal repair work, were unable 
to cope with the flood of fungus-infected instruments 
which descended upon them. Many types of instru- 
ments lasted only from four to eight weeks before 
becoming infected. Not only were instruments in use 
becoming infected, but new instruments awaiting 
issue in depots were found to be deteriorating rapidly 
on the shelves because of fungal attack. It was fre- 
quently necessary to clean and overhaul binoculars 
wliich had been reconditioned only a few weeks before. 
New or reconditioned binoculars which were shipped 
from Australia were found to be infected before they 
were issued from New Guinea depots. 

32 STATEMENT OF PROBLEM 

The various reports which are cited as references, 
as Avell as others to which no specific reference is 
made, indicate that under tropical conditions deterio- 
ration of one form or another occurs in the metal 
bodies of instruments, lenses, and prisms, as well as 
in lutings, greases, paints, gaskets, and other mate- 
rials such as cork and rubber which may be used. Also, 
leather, metal, and canvas used for carrying cases may 


be seriously atfected. In general, deterioration may be 
due to moisture alone or moisture in combination with 
fungus. No matter what the specific effect on any of 
the materials might have been, these effects did not 
prove to be serious, insofar as the function of instru- 
ments was concerned, until the glass surfaces them- 
selves were obscured. This was a somewhat paradox- 
ical situation in that fungi fouled glass most rapidly 
in service, although glass, along with metal, is itself 
least able to support fungus growth. 

According to OSRD Report 4118,^ fouled optical 
glass can interfere with the efficient operation of an 
instrument in two Avays: (1) by interference and 
loss of light if the tarnished area is continually in 
focus, and (2) by causing permanent etching of the 
glass Avhen such fouled areas are allowed to remain 
without cleaning. That report defines and discusses 
the main types of tarnish on glass surfaces which re- 
sult from exposure to a hot humid climate. These are 
(1) physical and chemical changes in the glass sur- 
faces resulting from prolonged exposure to humid air 
and condensed Avater, (2) the distillation of oily sub- 
stances upon optical surfaces, and (3) the groAvth of 
fungi over the glass surfaces. The distillation of sub- 
stances is also cited as an important factor in deterio- 
ratioji in a report from the United Kingdom.^ 

The corrosion of optical glass by moisture is con- 
sidered in OSRD Report 6055.^ This information is 
taken largely from a previously published report,'^ 
and its revieAV is given beloAv. 

Water Attack In the presence of high concentrations of 
AA'ater vapor, the more soluble constituents of the glass migrate 
to the surface. If the amount of liquid AA^ater present on the 
surface is too little to dissolve the resulting hydroxides and 
carbonates, a slushy layer of crystals is formed. The loss in 
transparency may be slight in the case of a soda-lime-silicate 
AvindoAv glass that forms scattered crystals of visible size, or 
the loss may be great in the case of a lead silicate glass Avhere 
the crystals are microscopic in size and cover the surface com- 
pletely. The rate of dimming depends on the composition of 
the glass. One month of exposure to humidity conditions of 
the type found in a tropical warehouse during the rainy season 
Avill cause barely visible dimming of the most durable glass 
compositions and Avill cause the most unstable glass compo- 
sitions to become translucent instead of transparent. 

The United Kingdom ReporD gives the folloAving 
consideration to Aiming or dimming of optical glass 
by moisture. 


PROBLEMS RELATED TO FUNGUS 


19 


The polished surface layer of glass has some properties 
differing markedly from those of the bulk of the glass. For 
example, the refractive index of the polished layer is, in gen- 
eral, quite considerably higher than that of the rest of the 
glass; further, the polished surface of the glass may be rela- 
tively unstable and, in particular, especially with crown 
glasses, free alkali may be present in the polished surface. In 
consequence, many polished surfaces have a natural affinity 
for water and if exposed to an atmosphere of relative humidity 
50% and upwards will have a water inclusion in the surface. 
(In such circumstances the surface electrical conductivity 
becomes easily measurable.) The attracted water extracts more 
alkali from the glass and if the surface is subjected to con- 
ditions involving a cycle of varying humidity, successive 
solution and drying-out of alkali will take place and this may 
eventually result in the formation of a visible film. With many 
glasses this film is readily removable by wiping, but with others 
actual etching of the surface takes place. In barium and flint 
glasses, the metallic oxide content of the polished layer is 
higher than the normal for the glass and, as a result of ex- 
posure to atmospheric conditions, visible tarnishing may 
occur. 

The Australian report^ refers to the conclusions of 
one investigator with reference to the properties of 
glass surfaces and their relationship to staining and 
etching. These are as follows. 

(a) All silicate glasses are very active and react in a fraction 
of a minute with water, giving on the surface of the glass a 
colloidal layer of silicic acid as a result of hydrolysis of silicates ; 
the layer protects the glass from further decomposition by 
water. 

(b) The thickness of this layer varies between 11 and 60 
Angstrom units (1 A. U.= 10"* cm). 

(c) The colloidal layer is capable of absorbing other colloidal 
particles and electrolytes by 'exchange absorption.’ That is 
to say, substances in the glass surface are replaced by others 
originally present in liquid in contact with the surface. Pre- 
sumably this is the cause of the staining of glass caused when 
weak acids are left in contact with the surface. 

Staining and etching of glass surfaces then may be possibly 
caused as follows: 

(a) By the action of acids such as are known to be secreted 
by fungal cells (e. g. carbonic, citric, oxalic). Some plant cells 
have the power of absorbing ions from extremely dilute con- 
centrations (energy necessary coming from the respiratory 
process), even to the extent of reducing the conductivity of the 
water around them to that of the purest ‘conductivity water.’ 
If fungi also have this power, continued solution of substances 
from the glass might occur, leading to real etching. 

(b) By exchange absorption of ions between the living cell 
and the glass surface, similar to that which takes place between 
roots and clay particles. 

It is evident, therefore, that the fouling or dimming 
of glass by moisture alone is neither unique nor to be 
unexpected, and that it is the property of the glass 
itself which makes it particularly susceptible to foul- 
ing by moisture alone. 

33 PROBLEMS RELATED TO FUNGUS 

The foregoing section indicates the deterioration of 
optical glass which results from moisture alone, but 


the quickest and the most striking type of deteriora- 
tion of optical glass is that which results when fungi 
grow on or over the glass surfaces. When fungi are 
present in optical instruments, they are either obtain- 
ing nourishment from materials which are a part of 
the instrument or from foreign substances inside the 
instruments, such as dust or minute animals such as 
mites. It has been demonstrated^’^’ that under proper 
moisture conditions fungus spores which are present 
on clean glass surfaces are able to give rise to suffi- 
cient mycelium to be troublesome by using only the 
stored food which is present in the spores. Under con- 
ditions which favor more i^rofuse growth of fungi, 
lenses or prisms may become opaque, wholly or in 
part, and markedly decrease the efficiency of the 
instrument. 

The sources of infection of optical instruments by 
fungus spores have been indicated in the various re- 
ports on the subject. One such source is infection dur- 
ing assembly and repair. Fungus spores which gain 
entrance to the instrument during these operations 
remain there and give rise to mycelial growth when 
conditions for their germination become favorable. 
Another likely channel of infection is by means of 
growth of mycelium through holes or luting of the 
instruments. A mycelium which penetrates the instru- 
ment in this fashion may arise from spores which are 
in the luting materials or from spores present in in- 
strument cases. It is possible for mycelia outside an 
instrument to penetrate the instrument through holes 
or cracks present in the luting or by digesting a path 
through the luting. Early observations on infected in- 
struments indicated that minute animals, particularly 
mites, might play an important role in the infection 
of instruments. There has been no common agreement 
with reference to the significance of mites in the infec- 
tion of optical instruments even though this topic 
has been widely discussed.^’®’®*'^’® 

It has been pointed out®’® that some of the fungi 
which have characteristically been found in optical 
instruments produce a certain type of opaque fruiting 
body (perithecium) which may have been mistakenly 
identified as mites, thereby overemphasizing the sig- 
nificance of mites in the infection of instruments. The 
majority of those who have studied the problem 
would concede that mites can and do furnish a likely 
source of infection, but on the basis of the reports 
which have been made, it seems that more evidence 
is necessary before mites can be regarded as a major 
factor in the infection of optical instruments by fungi. 

Much attention has been given to the fungi which 


20 


DETERIORATION OF OPTICAL INSTRUMENTS 


have been isolated from infected instruments. The 
o})inion was cx})ressed early in the Avar that tliese fungi 
may consist of special forms or possess special prop- 
erties AAdiieh Avould peculiarly adapt them to the de- 
terioration of optical instruments. HoAA^ever, as more 
information concerning these causative organisms AA^as 
obtained, it Avas shoAvn that the fungi involved in the 
deterioration of optical instruments did not represent 
special types nor did they possess any special proper- 
ties. To be specific, fungi AA'hieh have been isolated in 
Australian investigations are primarily species of As- 
pergillus and Penicillium. Of the fungi isolated from 
infected instruments returned from the Panama Canal 
Zone,^ those Avbicb are judged to be most significant 
in the fouling of glass in the Canal Zone are Monilia 
and several species of Penicillium and Aspergillus. 
The fungi AAdiich have been identified during studies 
in British "West Africa^ as being most significant in 
the infection of optical instruments are MoniUa siio- 
phiJa, Aspergillus uiger, and an unidentified species of 
Penicillium. From the above, it can be seen that the 
fungi AA'bicb are primarily involved are merely ‘The 
Avceds of the fungus AvorbP’ and in no sense do they 
constitute any special group of organisms. 

3 4 RELATIONSHIP OF MOISTURE 
PROBLEMS TO FUNGUS PROBLEMS 

The conditions necessary for the development of 
fungi in ojitical instruments^’^ have been briefly dis- 
cussed. Over and above the general food requirements 
for fungi AAdiich have been mentioned above, the prin- 
cipal essential requirement is that of a rather high 
relative humidity. It has frequently been stated that 
relatiA’e humidities of approximately 70 per cent or 
higher are necessary in order for groAvth of fungi to 
occur. It is obvious, therefore, that if the moisture 
conditions Avitbin optical instruments can be con- 
trolled so that relative humidities of 70 per cent or 
higher Avoiild never lie attained, most fungus problems 
Avoiild also lie controlled. Initially and tbroiighoiit 
most of World War II, boAvever, investigations on the 
prevention of deterioration of optical instruments 
have been organized primarily around the control of 
fungus. At the outset, fungus problems AA^ere most 
easily detected and more spectacular and, fiirtbermore, 
damage as the result of fungus action became more 
serious in a shorter period of time. 

It is certainly conceivable that instances of moisture 
damage such as fogging or filming can occur Avithout 


fungus fouling. These elTeets may he temporary. For 
example, exposed instruments, having been subjected 
to heavy condensation during periods of Ioav tempera- 
ture in humid tropical areas, AA^ould have abundant 
condensed Avater on internal optical surfaces, making 
the instrument completely unusable until that Avater 
bad vaporized AAdien the temperature Avitbin the instru- 
ment Avas raised. Moisture effects such as fogging or 
filming could also occur Avitbout fungus fouling. 
Table 7 of OSRD Report 4118^ summarizes the in- 
cidence of fogging and fungus infection as AA^ell as 
other characteristics for experimental binoculars 
Avbicb Avere exposed for the most part in Panama, 
(^omment on the fogging of fungicidally treated in- 
struments Avill be made later. These data illustrate 
that although fogging and filming may occur Avitbout 
fungus infection, they are more generally accompanied 
by it. This Avas particularly true of untreated instru- 
ments Avbicb AA^ere used as controls. 

3.4.1 Moisture Accumulation by 

Optical Instruments 

L'nlcss special precautions of sealing or dessication 
of optical instruments are taken, the design and con- 
struction of the instruments is of such a nature as to 
lead to an accumulation of moisture Avitbin the instru- 
ment in humid tropical areas Avbere there is a marked 
temperature differential betAATen days and nights. 
High tempei’atures during the day expand the air 
AAutbin instruments and force it out through small 
pores or apertures. When the temperature falls, mois- 
ture-laden air is draAAui into the instrument. During 
subsequent “breathing’^ of the instrument as a result 
of marked fluctuations in temperature, moisture is 
not removed from Avithin the instrument in the egress 
of air under high-temperature conditions. Such an 
accumulation of moisture provides fungus spores or 
filaments Avith sufficient moisture to satisfy their 
groAvth requirements. Different types of optical in- 
struments have common features of design AAdiich give 
rise to such breathing. Although the emphasis in the 
program Avas placed on the deterioration of binocu- 
lars, it should not be interpreted that other types of 
optical instruments are not subject to moisture and 
fungus deterioration. Among those AAdiich have been 
reported in OSRD Report 4118 as shoAving fungus 
spotting during field observations in Panama are ob- 
servation and director telescopes, range finders, 
height finders, and cameras. 

Since optical instruments are susceptible to the 


CONTROL MEASURES 


21 


effects of moisture, once moisture makes ingress, an 
ideal environment is created for the rapid develop- 
ment and serious consequences of fungus growth. It 
may be reasoned that absolute control against the 
entrance of moisture would have been a more funda- 
mental approach than control of fungus, but the fact 
cannot be disregarded that the controls against fungus 
which have been developed have greatly extended the 
service life of instruments. 

3.5 CONTROL MEASURES 

^ General Considerations 

In the foregoing, the problem of deterioration of 
optical instruments has been stated as it has been 
visualized in the United States and Allied countries. 
Reference has been made to the more important re- 
ports from these sources to illustrate specific points 
of view and the emphasis and trends of the programs 
in the respective countries. It should be borne in mind 
that Australian, British, and United States work has 
been based upon field exposures in different tropical 
regions. There is no particular reason to believe that 
the field conditions in these regions are so marked in 
their differences that they significantly affect the eval- 
uation of the contrasting methods of protection which 
have been developed. As will be pointed out, the most 
striking difference in results has been obtained from 
the exposure of instruments treated with Merthiosal 
in New Guinea and Panama. New Guinea exposures 
show that Merthiosal gives good protection against 
fungi whereas Panama exposures show that Merthio- 
sal-treated instruments were less satisfactory than in- 
struments treated with other fungicides. Such con- 
trasting performances can perhaps be explained by 
differences in materials and their application, or by 
differences in test instruments rather than by exposure 
in different geographical regions. This seems to em- 
phasize the desirability of a testing program in which 
comparable specimens would be exposed in different 
tropical areas. Such a program would certainly serve 
as an adequate basis for evaluating the different con- 
trol measures which have been proposed. Furthermore, 
such a program would indicate the significance, if 
any, of local or regional climatic differences. 

In the following sections further reference will be 
made to results of Allied investigations, but the prin- 
cipal emphasis will be given to the organization and 
results of the program as carried forward by TDAC 


and NDRC Section 10.1 which conducted the early 
investigations. 

Sanitation Methods 

Among the possible methods for controlling the de- 
terioration of optical instruments are those which arc 
indicated under the heading ^‘Sanitation Methods” in 
OSRD Report 4118.^ These are aimed at the elimina- 
tion of all materials which would serve as sources of 
food for fungi and would include the elimination of 
infection during factory assembly and during recon- 
ditioning and repair. Therefore, if cork or paper pads 
are used in instruments they should be treated with 
a suitable fungicide. Likewise, the leather which is 
used in cases, straps, etc., should be given fungicidal 
protection. Among the effective fungicides recom- 
mended for this purpose are salicylanilide as indicated 
in Tentative Specification AXS-1416 Ordnance De- 
partment, U. S. Army, paranitrophenol recommended 
by many investigators, and terpineol which proved 
successful in West Africa field trials.^® 

It has been much debated as to whether or not 
leather is actually harmed or deteriorated by fungus 
growth. That particular question does not enter into 
these considerations. Leather binocular cases which 
are heavily fungus infested provide a ready means of 
contaminating the instruments themselves. Successful 
attempts have been made to eliminate this source of 
infection by the substitution of plastic cases for the 
standard leather carrying cases. ^ 

In the cleaning and repairing of infected instru- 
ments, it is highly important to remove all traces of 
fungus growth not only from the prisms and lenses, 
but from the metal as well. For this purpose, ethyl 
alcohol and a stiff bristle brush can be used. The action 
of the alcohol is to kill all residual spores and all fila- 
ments are removed by the brush. If lenses need to be 
cleaned, lens paper dipped in alcohol will usually 
suffice. More refined methods for cleaning optical in- 
struments, however, have been given.^^ If slight etch- 
ing is present on optical surfaces, it may be removed 
by the use of rouge. The use of oil as a medium for 
rouge polishing should be avoided; if the oil gets on 
metal, it may redistill on the optical surface. 

AVhen optical instruments are serviced and repaired 
under field conditions it is only with great difficulty 
that the instrument can be kept free from fungus 
spores. This was recognized by the Australians and 
attempts were made to develop methods of treating or 


22 


DETERIORATION OF OPTICAL INSTRUMENTS 


sterilizing interiors of instruments after assembly.^ 
These methods showed some initial promise, hut they 
were eventually discarded. There is no question hnt 
that ideal conditions for assemhly and repair of instru- 
ments in operational areas Avould he air-conditioned 
workshops and laboratories employing methods sncli 
as those used in factory assemhly. 

3.5.3 Deliumidification and Sealing 

Deliumidification represents another approach to 
the deterioration-control problem in optical instru- 
ments. This is ideally accomplished by completely 
sealing the instrument in an atmosphere of sufficiently 
low relative humidity to exclude the moisture required 
to support the growth of fungi. In a well-sealed in- 
strument the low relative humidity within the instru- 
ment should he maintained since moisture-laden air 
cannot have access to the interior of the instrument. 
This presents no problem in large instruments which 
are well enough sealed to hold gas under pressure. 
The use of silica gel as a dehydrating agent has been 
successful in many instruments, hut details for its 
general usage are still to be worked out. 

The major problem in maintaining a low relative 
humidity occurs with those instruments which are 
designed to he sealed with a putty-like compound. 
Such compounds as have been used vary widely in 
their properties and degree of effectiveness. Compound 
FXS-779 has been generally the most widely used and 
the best, hut its performance has indicated that it is 
far from ideal. Satisfactory sealing of focusing eye- 
pieces has been obtained with waterproof greases. 

Considerable work has been directed toward devel- 
opment of new and more satisfactory sealing com- 
pounds. These investigations are described in OSRD 
Report 5684,^^ issued by TDAC. The requirements 
which a satisfactory sealing compound should fulfill 
are given in OSED Report 6055,^ as folloAvs. 

1. It should show excellent adhesion to metal surfaces and 
to glass. This adhesion should be retained after long aging. 

2. The compound should demonstrate sufficient cohesiveness 
so that cracking or separation under pressure may be avoided. 

3. The melting point should be below 300°F. 

4. The compound should not flow of its own weight below 
150°F. 

5. At — 60°F. it should not become brittle. However, any 
compound might be acceptable which became brittle at this 
temperature provided its properties of cohesion and adhesion 
were promptly restored when the temperature was raised. 

6. It should be easily applied both in the assembly line, in 
the optical repair shop and in the field. 

7. It should be possible to use the compound without the 
necessity of heating the surfaces to be sealed. 


8. It should contain no constituents which might volatilize 
and redistill upon glass surfaces with the production of a scum 
over these surfaces. 

9. It should not support fungus growth. If it does, this 
quality should be remedied by the application of a fungicide. 

10. It should not be water soluble or \vater permeable. 

11. Upon aging, the compound should not crumble or crack 
as a result of drying out. 


In the laboratory investigations on sealing com- 
pounds, nine commercial preparations were tested and 
all of them were unsatisfactory on the basis of one or 
more tests to determine their all-around fitness for 
use in oi)tieal instruments. In addition, over 75 new 
formulations were subjected to a series of fundamental 
tests. Many of these were discarded but the most prom- 
ising on the basis of these preliminary trials was sub- 
mitted to optical laboratories for further evaluation. 
The most promising compound has the following 
formulation : 

Darex thernioplast XTP-412 
(Dewey & Almy Chemical Co.) 

Darex thernioplast STP-378 
(Dewey & Almy Chemical C^o.) 

Microcrystalline lYax No. 2310 
(Socony Ahicuum Co.) 

Paranitrophenol 

On the basis of the overall performance of this 
compound as recorded in OSRD Report 5684,^^ issued 
by TDAC, it adequately meets the requirements nec- 
essary for efficient i)erfornianec of a sealing material, 
ddie only as})eets unfavorable to its use were those per- 
taining to its stickiness and 'stringiness, particularly 
in cleaning off excessive amounts after application and 
its removal during the disassembly of instruments in 
which it was used. However, as it is pointed out in the 
re})ort, so far as is known, it is virtually impossible to 
attain the essential characteristics of adhesion and 
cohesion except by use of a compound which would be 
sticky and stringy under these same circumstances. 


600 grams 


GOO grams 


120 grams 


13 grams 


3.5.4 Improved Storage Conditions 

Many observations of optical instruments in storage 
which have been reported^ indicate that the fungus 
problem is of significance during storage and precau- 
tions must be taken against it. Generally, where hu- 
midity is high fungus is found, and conversely, where 
humidity is controlled by air conditioning, fungus 
presents little or no problem. It is therefore obvious 
that air-conditioned storage space is highly desirable. 
This may well be practical at large bases or in ware- 
houses where the necessary facilities exist but at out- 
posts an entirely different situation is presented. For 


CONTROL MEASURES 


23 


safe storage of small quantities of instriiiiieuts at such 
outposts, a portable dry chest in which a low relative 
humidity is maintained by means of a lighted electric 
lamp has been described^® Likewise, nonportable dry 
chests can be readily constructed^ 

Problems connected with the long-time storage of 
optical instruments could probably be eliminated with 
the use of air-conditioned facilities. It is conceivable, 
however, that individual metal containers which were 
dehydrated or filled with an inert gas such as nitrogen 
would be better from certain considerations. It is 
understood that considerable investigation and appli- 
cation of this general method of long-time storage has 
been undertaken by the Army and Navy. Another 
approach to these problems which merits further con- 
sideration is the use of strippable films, either of the 
hot-dip or sprayable sort. Initial results of a promising 
nature were obtained by experimental applications 
of a hot-dip compound, but after 18 months’ exposure 
to drastic jungle conditions, it was indicated that the 
compound tried was not thoroughly satisfactory. This 
general method, particularly the use of such films 
which can be applied by spraying, has been widely 
used on all other kinds of equipment and its applica- 
bility should be investigated further with reference 
to both large and small models of optical instruments. 

^ Chemical Control 

Of the various approaches to the problem of fun- 
gus control in optical instruments, control by chem- 
ical means has been given most attention. Various 
chemical methods of control have been recommended 
and if these alone Avere used there Avould no doubt 
be a material increase in the service life of the instru- 
ments to which they Avere applied. HoAvever^ it was 
neA'er assumed that these chemical methods Avould by 
themselA'CS solve the problem. The best results from 
effective methods of chemical treatments can be ob- 
tained only AA^hen they are used in conjunction Avith 
methods directed to prevent deterioration by moisture 
alone. Furthermore, good sealing of instruments 
Avould prolong the effective period of a chemical treat- 
ment. Methods of chemical control have been directed 
to the control of mites as Avell as the control of fungus, 
on the basis that control of mites AAwld render infec- 
tion less likely. 

IIequirkments of Control Chemicals 

The requirements Avhich should be met by chemicals 
used for the control of mites and fungi in optical in- 


struments have been giveJi as folloAvs.® 

1. It should prevent all fungus development in an instru- 
ment. 

2. It should keep an instrument free of mites. 

3. It should be sufficiently lasting to protect an instrument 
for many months. 

4. It should not accelerate the normal moisture corrosion of 
metals used in optical instruments. 

5. It should not increase the fogging normally resulting 
from moisture in most optical instruments in humid tropics. 

6. It should not harm the finishes commonly employed on 
the surfaces of optical instruments. 

7. It should not harm the cements used for sealing compound 
lenses. 

8. It should present no health hazard to those employing 
the fungicide. 

Treatment of Glass Surface 

Experimental treatment of glass surfaces Avith inor- 
ganic salts or nonvolatile fungicides has not proven 
entirely successful. The attempt to use fluorides which 
are knoAAUi to be enzyme poisons did not prevent the 
groAvth and development of fungi in Australian ex- 
periments.- Camera lenses Avith a hard fluoride coating 
have been reported to shoAv heavy fungus groAvth and 
even etching through the hard surface. The germina- 
tion of fungus spores can apparently be controlled by 
certain treatments, except Avhen nutrition is gained 
from such sources as mites Avhich crawl upon the glass 
surface and die. Another approach Avhich has been 
made in this aspect of chemical control has involved 
the incorporation of fungicidal materials in antifog- 
ging substances Avhich reduce surface tensions. Suffi- 
cient promise to Avarrant further inA^estigation of this 
aspect of control has been obtained by incorporating 
Eoccal (high molecular alkyldimethyl-benzyl ammo- 
nium chlorides) to the extent of 50 per cent in an 
antifogging compound applied to lens surfaces. These 
treated instruments have remained perfectly clean 
after exposure for over a year in Panama while all 
untreated controls have become badly infected.^^ 

Merthiosal Treatment 

Previous reference has been made to the use of 
Merthiosal (sodium ethylmercuri thiosalicylate) in 
Australia for chemical control of deterioration of op- 
tical instruments.*^ Iiecommendations for its use Avere 
made after extensive investigations shoAved that it 
served to control fungus growth. The investigations 
included both laboratory experiments and NeAV Guinea 
field exposure tests. The compound is applied to in- 
struments in a lacquer with Avhich the interior metal 

®This compound is referred to in recent Australian reports 
as MTS (anti mould). 


24 


DETERIORATION OF OPTICAL INSTRUMENTS 


surfaces, cork, and other materials are painted, and 
is mixed with cements and luting materials. From ex- 
periments to determine the effect of Merthiosal on 
mites it was apparent that the compound did not 
function as a mite repellent, hut evidence was obtained 
that the compound will kill mites and reduce their 
numbers inside instruments. It was also noticed that 
fungus spores present on the dead bodies of mites did 
not develop. The general results of tests to determine 
the corrosive tendencies of Merthiosal when used with 
waxes, greases, or lacquers indicated that Merthiosal 
did not affect the protective power of paint in a 2 
per cent concentration, nor did it accelerate metallic 
corrosion. 

Contrasting results were obtained with Merthiosal- 
and Cresatin-treated instruments with reference to 
the prevention of fungus growth, the acceleration of 
corrosion, and the ability to repel mites. The differ- 
ence between the performance of Merthiosal in Pan- 
ama and Australia may well be due to slight differ- 
ences in application of the materials used, as has been 
suo:o:ested. The nature and construction of the test 
instruments may also be an important factor, par- 
ticularly in regard to the quality of the seal which 
can be made.^ Further comparisons are necessary in 
order to determine the reasons for the discrepancy. 

Two of the materials synthesized in Australian 
laboratories and closely related to Merthiosal have 
given more satisfactory results in Panama tests. These 
materials are ?? -butyl (ethylmercuri) thiosalicylate 
and methyl (ethylmercuri) thiosalicylate. They have 
both protected binoculars against fungus infection 
for a period of eight months, but the methyl deriva- 
tive has induced considerable corrosion of aluminum. 

Ckesatin Treatments 

In contrast to the use of Merthiosal by Australia 
in chemical control of fungus, Cresatin (metacresyl 
acetate) has been widely used in the United States. 
The early field experiments^’ which led to recommen- 
dations for its use have been described. Specific rec- 
ommendations for its use have been made^^ and a more 
complete report^’^^ of the experimental program, par- 
ticularly the results of long-time exposure tests, has 
been given. Tn early laboratory tests Cresatin showed 
promise over many other compounds, and as a result 
the field program in Panama was set up. The results 
of these exposure tests have served to strengthen and 
confirm the early laboratory results. Various methods 
of applying Cresatin in optical instruments^ have been 


reported. The most promising method consists of in- 
corporating Cresatin into ethyl cellulose to make a 
solid taffy-like block. The initial concentration of 
fungicide used in the mixture was 25 per cent. In an 
instrument, the block was fastened to the inner sur- 
face of the metal covering plate with an adhesive. As 
a result of further investigations similar Cresatin- 
ethyl cellulose mixtures, containing 50 per cent of 
the fungicide, were applied in aluminum capsules 
which were affixed to covering plates with cement 
after the capsule ends were crimped. The higher con- 
centration gives a greater reservoir of the fungicide 
and enables a treatment to last for a longer period. 
By crimping the ends of the capsules only small pores 
which permit a gradual escape of the fungicide re- 
main. Details of the use of these capsules in various 
types of optical instruments are given in OSRD Re- 
port 3803.^^ A 1945 report^ ^ indicates that Cresatin 
has kept binoculars free of fungus and mites in Pan- 
ama exposures for 21 months. The early exploratory 
laboratory tests showed that Cresatin both kills and 
repels mites. 

A quantity of 500,000 fungicidal Cresatin capsules 
were procured by Frankford Arsenal and distributed 
throughout the Pacific area for application to instru- 
ments during servicing and repair. 

Considerable attention was directed toward the pos- 
sible corrosive action of Cresatin. Upon hydrolysis of 
the compound, acetic acid is formed which will in- 
crease the normal moisture corrosion of brass, steel, 
zinc, and aluminum. This possibility has been freely 
discussed and openly considered in reports which have 
been made on the use of Cresatin in optical instru- 
ments. Most of the objections to the use of Cres- 
atin on these grounds were raised before the alumi- 
num-capsule method of application Avas developed. 
With the inclusion of the Cresatin-ethyl cellulose com- 
pound in the aluminum capsules the possibility of cor- 
rosion of metals by the fungicide Avas greatly reduced. 
Field observations confirmed laboratory tests AAdiich 
shoAved that normal moisture corrosion of treated in- 
struments is no more severe than if instruments are 
untreated and in many cases less severe. Investigations 
at Frankford ArsenaP^ shoAved that Cresatin in a 
1/10,000 concentration at 104 F and saturated hu- 
midity does not harm metals and finishes used in 
optical instruments. In many instances where cor- 
rosion has been observed in field exposure of Cresatin- 
treated instruments, there Avere indications that this 
corrosion resulted because Cresatin Avas applied in 
excessive quantities and in such a manner that electro- 


CONTROL MEASURES 


25 


lytic action on metals resulted. Among the instances 
where corrosion of experimentally treated instruments 
was observed in field exposure this corrosion was no 
greater than that present in untreated instruments 
and, furthermore, the treated instruments remained 
usable long after most of the untreated controls had 
become badly fungus fouled. United Kingdom rec- 
ommendations^ stated that a 25 per cent concentration 
of Cresatin in ethyl cellulose gives no serious corrosion 
in optical instruments. This concentration is not as 
high as that recommended in the later work of TDAC, 
but the higher concentration (50 per cent Cresatin) 
has proven to be thoroughly satisfactory in short-time 
experiments. Only long-time tests which adequately 
evaluate fungus protection against possible corrosion 
will determine the limits within which Cresatin can 
be used to control the fungus fouling of optical in- 
struments. 

Other possible objections to the use of Cresatin have 
been indicated. Excessive concentrations of the fungi- 
cide may prove deleterious as a result of the solvent 
action on lens cements, since those commonly used 
are soluble in Cresatin. Only one instance of this diffi- 
culty was encountered in the numerous trial treat- 
ments at the University of Pennsylvania and in Pan- 
ama, but an excessive concentration of Cresatin vapor 
was used. Laboratory exposures at Frankford Ar- 
senaP^ and in England^*'’ have indicated that lens and 
prism cements are affected by Cresatin. A possible 
method of eliminating such effects is by the appli- 
cation of films of polyvinylidene chloride to the edges 
of lenses. 

Thanite Treatments 

There was developed as a result of other investiga- 
tions a method of treating optical instruments based 
on the use of a contact fungicide and mite repellent.^^ 
It was visualized that this would be useful primarily 
to field service repair men and for instruments already 
in tropical service to which a vapor phase fungicide 
such as Cresatin could not readily be applied. Many 
compounds were screened by the use of a test method 
employing mites,^® and the most promising of these 
compounds were subjected to other tests which would 
determine the dimming or condensation on optical 
surfaces. As the result of these tests, Thanite (fenchyl 
thiocyanoacetate) was given further trial when ap- 
plied to instruments and finally recommendations 
were made for its general use. The recommended ap- 
plication is in a water soluble grease of the following 


formulation for screw threads, screw heads, and seal- 
ing end plates. 

Carbowax 4500 65 parts 

Carbowax 1500 35 parts 

Sodium chromate 1 part 

Fenchyl thiocyanoacetate 2 parts 

In addition the following mixture is recommended 
for coating all interior surfaces of optical instruments. 
Methyl alcohol 70 parts 

Shellac 30 parts 

Fenchyl thiocyanoacetate 2 parts 

For nonrefiective glass surfaces, a formulation as 
follows is suggested. This mixture should be incorpo- 
rated in the proportion of one part mixture to one 
part total lacquer solids. 

Asbestine 80 parts 

Boneblack 5 parts 

Santocell 15 parts 

This experimental treatment has been applied to 
far fewer test instruments than has the Cresatin treat- 
ment, and exposure testing has for the most part been 
restricted to the specialized test employing extensive 
mite populations. There has been no indication that 
these tests have extended for a period any longer than 
four weeks. Only one instance is known of field-test 
results of optical instruments treated with fenchyl 
thiocyanoacetate. Among the instruments tested by a 
Frankford Arsenal mission to Panama in 1945 were 
two Ml 7 elbow telescopes treated with Thanite. The 
details of the treatment were not available. These tele- 
scopes were exposed for a 3V2-n^onth period ; one tele- 
scope showed marked fungus growth on the reticle 
and slight growth on the prism and the other showed 
a slight amount of fungus growth on the reticle. A 
control instrument showed considerable mold on most 
of the optical surfaces. Considering the limited appli- 
cation which has been given this fungicide with regard 
to both the quantity of instruments and the extent of 
actual field testing, there is no reliable basis upon 
which to base a comparison of such a treatment em- 
ploying this contact fungicide with treatments employ- 
ing Cresatin, a vapor phase fungicide. However, as 
indicated in Chapter 6, the Carbowax mixture con- 
taining fenchyl thiocyanoacetate has been widely ap- 
plied to threads of photographic lens elements in the 
South Pacific area and has been successful in prevent- 
ing the ingress of fungus and mites into these lens 
systems. 

Only slight information is available on the corrosive 
action of fenchyl thiocyanoacetate. In the original 
experiment, it is reported that corrosion of treated 


26 


DETERIORATION OF OPTICAL INSTRUMENTS 


instruments is no greater than, and if anything less 
than, untreated instruments/^ In a report from Eng- 
land^^ it was considered that the corrosive action of 
fenchyl thiocyanoacetate on copper, brass, and stain- 
less steel was approximately the same as that of meta- 
cresyl acetate. Aluminum was not shown to be affected. 

IxHiBiTorvY Radiations 

A general statement^ concerning this method of 
control of fungus infection has been given. In this 
method radium or radioactive salts are used. The 
alpha particles which emanate from such materials 
appear to be very effective in preventing any fungus 
growth. The incorporation of radioactive salts into a 
lacquer to be used in the vicinity of optical parts has 
been tried with considerable success. Perhaps a more 
effective method is the use of a radium foil which 
may be incorporated into the lens mountings in such 
a way that the stream of alpha particles comes into 
contact with the glass surfaces. 

The Engineer Board has conducted extensive in- 
vestigations at Fort Belvoir-® on this method of ap- 
plying radioactive materials to optical instruments. 
Results of only one field trial of this treatment are 
available. The Erankford Arsenal mission to Panama 
exposed one binocular treated in this fashion and one 
of the chambers became mold infected in the 3y2- 
month exposure period. This method of treatment does 
not repel mites, and it is therefore possible that dead 
mites may appear on otherwise clean glass surfaces. 
Furthermore, adequate sealing is necessary in order 
to prevent dimming of glass by water vapor. 

36 RECOMMENDATIONS FOR NEW 
DESIGN 

The various controls of the deterioration of optical 
instruments which have been presented in the fore- 


going section have been developed primarily as a 
means of protecting old-model instruments. Various 
reports have pointed out the importance of design in 
combating the problems. Design is not only impor- 
tant with reference to the deterioration of new instru- 
ments, but also in permitting service and repairs. As- 
sociated with the improvements which can be achieved 
by new design is the choice of materials which in 
themselves are resistant to deterioration. The possi- 
bility that plastic fixed focus binoculars would prove 
highly efficient in tropical service was recognized from 
the start. Many comments have been made on the suit- 
ability of late-model Army binoculars for performance 
in the tropics. These newer instruments, although not 
immune to tropical deterioration, have proven to be 
much more satisfactory than the old-style instruments, 
many of which were in use. The investigations which 
have been made have had as their primary objective 
the protection and improvement of the service life of 
these old-style instruments which were used out of 
necessity. The many approaches to the problem and 
the different treatments in themselves will not entirely 
eradicate deterioration ; in practice, each different 
form of approach or method is supplementary to 
others, i.e., satisfactory chemical controls are most ef- 
ficient only with proper sealing. 

Of the various methods recommended, all have not 
been given equivalent field trial. There is no reason 
to assume that the most promising of these methods 
which have been developed to date are the best which 
can be obtained. Once promising results were obtained 
in the investigations undertaken, a search for new and 
better remedies was continued. This attitude should 
continue to be held. Furthermore, complete compara- 
tive evaluation of field performance of the various 
treatments should also be made. Attention has fre- 
quently been called to the importance of field evalua- 
tions and this cannot be overemphasized, for accurate 
interpretations of effective preventive treatments can 
only he drawn from field evaluations. 


Chapter 4 

TROPICAL DETERIORATION OF TEXTILES 


4.1 INTRODUCTION 

T he fact that much emphasis and attention was 
given to the deterioration of military textile and 
cordage items by microorganisms during World War II 
should not create the impression that the deterioration 
of these materials has only recently been recognized. 
The deterioration of textiles l)y microorganisms is a 
problem of long standing but one to which little at- 
tention has been given in the United States until re- 
cently. England, on the other hand, because of her ex- 
ports of textiles to the Far East, and her numerous 
island possessions, recognized the necessity of protect- 
ing her shipments at least during transit and storage 
and developed an interest in fungus-pi’oofing at an 
early date. 

Much research has been done on the microbiological 
degradation of textiles. Prior to 1920 most published 
accounts on mold or mildew damage of textiles and 
cordage were concerned primarily either with a report 
of damage done or with the identification of the types 
of organisms involved. Since about 1920 there has 
been a much larger volume of work in this field, and 
considerable emphasis has been given to the develop- 
ment of methods for the prevention of damage to tex- 
tiles and cordage by microorganisms. It is not the in- 
tent to review this early work on the subject; a com- 
prehensive bibliography^ prepared during World War 
II includes significant references to past work in the 
field. 

Before World War II, the interest of textile manu- 
facturers, of chemical manufacturers, and of consum- 
ers in the fungus-proofing problem was confined 
largely to the protection of such fabric items as shower 
curtains, awnings, and tarpaulins or the cordage em- 
ployed by the fishing industry. When it seemed likely 
that much of our participation in World War II would 
take place in the Southwest Pacific, where the prob- 
lems of supply and maintenance would be of major 
concern, the Army and Navy recognized that large quan- 
tities of equipment, particularly sandbags and tentage, 
would be serviceable for only a relatively short time, 
unless protected by a fungus-proofing agent. Early in 
1941, certain branches of the Army and Navy initiated 
extensive programs to develop such preventive mate- 


rials and to test their efficiency in the different appli- 
cations required. Industrial laboratories, stimulated 
by the needs of the Army and Navy, expanded their 
research programs to find and develop new fungicidal 
materials, and as a result, new fungus-proofing com- 
pounds have been discovered and the uses for those 
already known have been considerably extended. By 
1944, when the Tropical Deterioration Administrative 
Committee [TDAC] was organized, much progress 
had been made toward a satisfactory solution of the 
textile deterioration problems presented by tropical 
warfare. 

OSRD Report 4513^ issued by TDAC points out 
all of the foregoing and reviews the pertinent infor- 
mation on the subject which was available at that 
time, including information from the United King- 
dom and Australia. 

4 2 CAUSES OF DETERIORATION 

The most important causes^ of the deterioration of 
textiles and cordage are : 

1. Photochemical degradation occurring in sun- 
light, particularly of cellulosic materials. Evidence 
would seem to indicate that not only cellulose itself 
may be affected by sunlight but also that the chemical 
agents which are added may be catalyzed to bring 
about changes which in turn may contribute to the 
degradation of cellulose. 

2. Direct reaction under certain conditions between 
fabric and other materials such as finishing com- 
pounds, components of soil, or other substances with 
which the fabric or cordage may come in contact. 

3. Deterioration by microorganisms which utilize 
the fabric or components of the finish as a source of 
food. These organisms may be capable of destroying 
the fabric directly or only of decreasing the effective- 
ness of the protective materials so that other factors 
then may operate to bring about deterioration of the 
fabric itself. 

The TDAC studies have been largely concerned with 
microorganisms; however, in the course of these stud- 
ies, significant information on other causes of deteri- 
oration was revealed, and their importance has not 
been neglected. 


27 


28 


TEXTILE DETERIORATION 


4.3 NEED FOR FIELD STUDIES 

From information returned from operational areas, 
tlie existence of problems associated with the deterio- 
ration of textiles was substantiated. Sound criteria did 
not exist for evaluating the extent to which protective 
measures were adequate; furthermore, the problems 
which were presented were so complex and variable in 
nature that the need of analytical studies in the field 
was apparent. Accordingly, plans were made whereby 
such studies were to be undertaken in the Southwest 
Pacific area, but unfortunately, after the personnel 
and equipment for these studies were assembled, it 
was not possible to proceed. 

4.4 FIELD STUDIES IN PANAMA 

As an alternative, arrangements were made to con- 
duct these field studies in Panama and the investiga- 
tions which were intended to be made in the Southwest 
Pacific area were undertaken at Barro Colorado Island 
under the direction of TDAC. The general climatic 
characteristics of Panama and Barro Colorado Island, 
as well as the detailed climatic conditions which per- 
tained during the period of test, are given in OSRD 
Report 4807.® The factors of rainfall, relative humid- 
ity, and wind movement, and their effects upon the 
results of the test are reviewed. In summarizing the 
influence of climatic factors on the results of the tests 
which were conducted at Barro Colorado Island, it was 
concluded that climatic conditions were not severe in 
terms of certain other humid tropical climates. If the 
significance of rainfall as the most important single 
factor in determining the deteriorative influence of a 
tropical climate is considered, it may be seen that 
other humid tropical areas have more severe climates 
than the Canal Zone. The occurrence of a dry season 
in Panama restricts the application which can be made 
of the test results in terms of performance in equa- 
torial regions which have a heavy rainfall throughout 
the year. However, the occurrence of a dry season 
proved to be valuable with reference to certain aspects 
of the performance of the test materials. 

^ Materials Used 

For these field investigations on textile materials, 
tlie Office of the Quartermaster General furnished an 
elaborate series of panels, chiefly heavy tent duck and 
light cotton sheeting, treated with thirteen different 
mildew-proofing compounds and including suitable 


untreated controls. The specific treatments which were 
given to the individual panels are given below with 
the code numbers used to identify the panels. 


Heavy Duck (11.9 oz) 


C-51 Control series bearing no fungicide. The fabric 
finish consists of the Jeffersonville Quartermas- 
ter Depot [JQD] No. 242 finish of the follow- 
ing general composition : 

42 per cent chlorinated paraffin 26 per cent 

70 per cent chlorinated paraffin 13 per cent 

Amberol M-88 (phenolic resin) 6.66 per cent 

Rubbery pitch (asphalt) 3.7 per cent 

Antimony oxide 20 per cent 

Calcium carbonate 12 per cent 


This mixture is applied in a single bath treatment 
with all ingredients incorporated in the mixture. The 
duck is dipped in the liquid (hydrocarbon solvent) 
and scraped free of excess. 

C-52 Standard tent duck treated with the above JQD 
No. 242 finish but containing copper naphthe- 
nate incorporated in the finish to the extent of 
0.35 per cent by weight of metallic copper. 

53 Standard tent duck treated with the above JQD 
No. 242 finish but containing, incorporated in 
the finish, 0.175 per cent by weight of copper as 
copper naphthenate and 0.175 per cent by 
weight of copper as copper hydroxynaphthenate. 


Shelter-Tent Duck (7 oz) 

C-54 Control series bearing no fungicide. The fabric 
is finished with a two-bath water repellent con- 
taining mineral wax and aluminum acetate. 

55 Shelter-tent duck treated with tetrabrom ortho- 
cresol so as to give 2 per cent by weight of the 
compound on the finished fabric. Two-bath 
water repellent containing mineral wax and 
aluminum acetate. 

56 Shelter-tent duck treated with phenyl mercuri- 
triethanolamine lactate so as to give 0.45 per 
cent by weight of metallic mercury on the fab- 
ric. One-bath water repellent, Fabrisec A A, 
containing wax emulsion only. 

57 Shetler-tent duck treated with dihydroxydi- 
chlorodiphenylmethane so as to give 2 per cent 
by weight of the fungicide on the fabric. Two- 
bath water repellent containing mineral wax 
and aluminum acetate. 

58 Shelter-tent duck treated with copper ammoni- 
um fluoride so as to give 1 per cent by weight 


FIELD STUDIES IN PANAMA 


29 


of copper on the finished fabric. One-bath water 
repellent of Fabrisec A A containing wax emul- 
sion only. 

59 Shelter-tent duck treated with trimethyloctade- 
cyl ammonium pentachlorophenate so as to give 
2 per cent by weight of the compound on the 
fabric. Two-bath water repellent containing 
mineral wax and aluminum acetate. 

60 Shelter-tent duck (9y2-oz Oxford) of a some- 
what higher tensile strength than samples 54 
to 59. Treated with copper 8-hydroxyquinoline 
so as to give 0.31 per cent by weight of copper 
on the finished fabric. 

Cotton Sheeting (of Varying Weights) 

C-1 Medium-weight sheeting with dye only. No 
water repellent or fungicide. 

IT Same fabric with dihydroxydichlorodiphenyl- 
methane applied in a two-bath treatment. Water 
repellent. 

1 Same fabric with dihydroxydichlorodiphenyl- 
niethane applied in a one-bath treatment. Water 
repellent. 

C-2 Medium-weight sheeting with dye only. No 
water repellent or fungicide. 

2 Same fabric with tetrabrom orthocresol. Water 
repellent. 

C-3 Medium- weight sheeting with dye only. No 
water repellent or fungicide. 

3PW Same fabric with 1 per cent Permacide AM- 
10 (a phenyl mercury compound). Water re- 
pellent containing wax only. 

3PP Same fabric with 1 per cent Permacide AM-10 
plus 2 per cent Perma Par E. Water repellent. 

C-4 Heavy-weight sheeting with dye only. No water 
repellent or fungicide. 

4N6 Same fabric with copper naphthenate applied 
as emulsion. Water repellent. 

4NH Same fabric with copper hydroxynaphthenate. 
Water repellent. 

4C Same fabric with copper as copper naphthenate 
applied in hydrocarbon solvent. Water repellent. 

C-5 Medium-weight sheeting with dye only. No 
water repellent or fungicide. 

5 Same fabric with trimethyloctadecyl ammoni- 
um pentachlorophenate. Water repellent. 

C-6 Medium-weight sheeting with dye only. No 
water repellent or fungicide. 

6PC Same fabric with 3 per cent pyridyl mercuric 
chloride. Water repellent. 


GPS Same fabric treated with 1 per cent pyridyl 
mercuric stearate. Water repellent. 

C-7 Medium-weight sheeting with dye only. No 
water repellent or fungicide. 

7M Same fabric treated with 25 per cent phenyl 
mercury phenolate. Water repellent. 

7P Same fabric treated with copper as copper am- 
monium fluoride. Water repellent. 

8 Nylon netting with urea formaldehyde finish. 

9 Cotton netting, insect bar, with dihydroxydi- 
chlorodiphenylmethane. Water repellent. 

C-10 Heavy sheeting with (mineral) dye only. No 
water repellent or fungicide. 

10 Same fabric with mercury as phenyl mercuritri- 
ethanolamine lactate. Water repellent. (This 
set was oil soaked when received in Panama.) 
lOX Same fabric with mercury as phenyl mercury 
salt of 2-mercapto benzothiazole. Water repel- 
lent. 

4.4.2 Plan of Exposure and Study of 
Mycological Factors 

In these field tests identical duplicates of each sam- 
ple were exposed to four contrasting conditions of the 
natural environment: (1) exposure to full tropical 
sunlight, (2) exposure to shade, (3) exposure to con- 
tact with ground on the forest floor, and (4) exposure 
to burial in the soil. For each variation in treatment 
and for each of the four conditions of exposure, eight 
samples were supplied, making serial observations and 
determinations possible at eight different periods dur- 
ing the entire exposure. In all, 1,120 half-yard samples 
were used for these field studies which were followed 
closely for a period of 16 weeks and gave a preliminary 
indication of the efficiency of fabric treatment under 
tropical exposure. 

Beside obtaining a comparison of the efficacy of the 
various treatments given to the experimental textile 
panels, a major objective was to determine as far as 
possible in the field the identit}', the frequency, and 
the sequence of appearance of cellulose-destroying and 
other fungi on the variously treated textiles. To this 
end a total of approximately 1,200 cultures of fungi 
were secured from the various Quartermaster Corps 
samples in addition to 250 cultures which were ob- 
tained from other textile items of military equipment 
in the field and from decaying cellulosic plant mate- 
rials. After the isolation of these organisms, they were 
dispatched to laboratories in this country for further 


30 


TEXTILE DETERIORATION 


purification, when necessary, and identification. This 
laboratory phase of the investigation has involved con- 
siderable time and effort and it was not possible to 
complete the identification studies on the organisms 
isolated. However, valuable information was obtained 
on general aspects of the organisms involved. 


Observations 

Number of Fungi on Panels 

An effort was made to determine the relative abun- 
dance of fungi on a selected group of sun- and shade- 
exposure samples by estimating the total amount of 
mycelial growth which developed by the use of dif- 
ferent culture methods. Although the methods used 
were far from refined in their quantitative aspects, 
there was a surprisingly close agreement between 
comparisons made independently at different times. 
The following observations in these studies were made 
on culture plates prepared from sun and shade panels 
after 75 days^ exposure : 

1. The abundance of fungi on the variously treated 
sun-exposure samples follows the same general se- 
quence when measured on three different media. The 
shade samples show more variation, probably because 
of greater fungus-spore load derived from adhering 
particles such as fragments of wood, leaves, and in- 
sect feces. 

2. The control samples have a more abundant fun- 
gus flora than the treated samples in both sun and 
shade. 

3. The lowest number of organisms occurred con- 
sistently on plates made from the fabric treated with 
copper 8-hydroxyquinoline, both after sun and shade 
exposure. Certain plates from this treatment were vir- 
tually sterile with only occasional colonies of Penicil- 
lium sp. and a coral-pink yeast which appeared to be 
the dominant organism. 

4. Copper naphthenate, pyridyl mercuric chloride, 
and copper ammonium fluoride hold the fungus flora 
down to a low level under both sun and shade 
conditions. 

Differences in the relative abundance of fungi on 
material similarly treated but exposed to sun rather 
than shade are probably due to a variety of factors. 
Among these are breakdown and loss of fungicide by 
sun and rain, divergent pH reactions of the fabric, 
ability of certain organisms to withstand one set of 
conditions and not the other, and variations in the 


quantity of spores derived from fragments deposited 
on the fabric surface by wind or from nearby vegeta- 
tion. 


Dominant Organisms on the Textile Panels 


P)y carefully selecting from agar culture plates frag- 
ments of the organisms which were present in the 
greatest abundance, it was possible to obtain with con- 
siderable accuracy the dominant fungi which were 
pi’esent on the test panels. Limitations of equipment 
and time did not permit studies of this sort on all of 
the samples but it was possible to study the organisms 
from certain selected panels in this manner. The fol- 
lowing list of dominant organisms is taken from 
OSPD Report 4807,*'’ and the organisms were obtained 
from cultures made after the selected panels were ex- 
jiosed for 80 days to sun and shade. xAdditional obser- 
vations on the dominant fungi involved are given in 
OSRD Report 5081.^ 


Sun Exposure 
C-51 Fusarium 

Botryodiplodia 
theobromae 
52 Pullularia 


C-54 Pullularia 
Torula 

57 (No cultures 
prepared) 

60 Yeast, pink asporo- 
genous 

C-1 Pullularia 
Curvularia 
Diplodia 

4-C Pullularia 
Penicillium 

4-NH (No cultures 
prepared) 

5 (No cultures 
prepared) 

6-PC Pullularia 

7-P Pullularia 


7-M (No cultures 
prepared) 

8 Pullularia 

Nigrospora sphaerica 


Shade Exposure 

C-51 Botryodiplodia theobromae 
Fusarium 

52 Botryodiplodia theobromae 
Pullularia 
Torula 

C-54 Botryodiplodia theobromae 
Blakeslea trispora 
Pestalotia 

57 Pestalotia (This was the 
only organism which ap- 
peared on the medium.) 

60 Penicillium sp. 

C-1 Cladosporium 
Pestalotia 
Blakeslea trispora 

4-C Pestalotia 
Pullularia 
Penicillium 
4-NH Pestalotia 
Penicillium 
5 Pestalotia 
Pullularia 
6-PC Pullularia 
Torula (?) 

7-P Penicillium 
Fusarium (?) 

Pestalotia 
7-M Pullularia 

8 Blakeslea trispora 
Pestalotia 

Botryodiplodia theobromae 


Three outstanding facts are immediately evident 
from the above listing of dominant organisms: (1) 
the small number of species, (2) the predominance of 
the genera Pullularia and Pestalotia, and (3) the 


FIELD STUDIES IN PANAMA 


31 


i general absence from the list of any of the commonly 

[ used “test^^ organisms for measuring fabric deteri- 

oration. 

This list should in no sense be interpreted as an 
analysis of the fungal flora on the test samples. With 
I longer incubation of the plates a wide variety of other 

fungi appeared, differing as to the number of species 
on different treatments. These organisms which ap- 
I pear later may actually he present in considerable 

' force but are either less numerous than those which 

appear first or else react quite unfavorably to the me- 
dium. There is no question but that the medium ex- 
erts a highly selective action on the results of these 
experiments, and in order to establish beyond question 
the dominant organisms on the fabrics it would be 
well to employ three or four media. 

The extraordinary abundance of Pullularia, a highly 
polymorphic member of the Dematiaceae, is signifi- 
cant. This organism apparently has a high tolerance 
to copper and mercury compounds and is moreover 
able to withstand extreme environmental conditions 
such as are imposed by direct exposure to tropical sun. 
There is some information available which shows that 
Pullularia is capable of attacking cellulose, but the 
need for further tests on this point is indicated. There 
is a strong possibility that the Pullularia population 
is inordinately high because this fungus grew on the 
oil-soaked samples and on the oil-soaked areas of other 
samples to the virtual exclusion of other fungi. In- 
oculation by rain and wind from these Pullularia-rich 
areas of the fabric may explain the predominance of 
this form. 

The abundance of Pestalotia on the shade-exposure 
series is interesting in view of its absence from or scar- 
city on sun-exposed panels. This genus comprised 
nearly 10 per cent of the total number of organisms 
isolated from the Quartermaster Corps textiles at 
Barro Colorado Island. Certain species of Pestalotia 
are active cellulose destroyers, and the frequent occur- 
rence of the organism on duck and cotton sheeting 
treated with copper naphthenate and dihydroxydi- 
chlorodiphenylmethane is significant. Shade-exposure 
panels of shelter-tent duck treated with dihydroxydi- 
chlorodiphenylmethane yielded nearly pure cultures 
of Pestalotia, a fact which would indicate significant 
tolerance of Pestalotia to this compound. The possible 
tolerance of Pestalotia to a compound which is other- 
wise highly fungicidal would be well worth testing as 
an example of preferential fungicidal action. 

These dominant fungi represented only a small 
fraction of the total number of the 1,200 cultures 


which were isolated. The complete range of fungi pres- 
ent on the samples furnishes an interesting list from 
the standpoint of the practical problems involved as 
well as on a purely mycological basis. Certain hitherto 
unknown forms have been discovered. As of March 1, 
1946, complete identifications had not been made, 
but those which have been made include the majority 
of the fungi isolated. A preliminary listing of identi- 
fied forms is given in OSRD Report 4807^ and a more 
complete presentation of the later identification is 
found in OSRD Report SGSl.'^ 

Generalizations concerning the Fungus Flora 

From the observations and the experience gained 
during the course of isolating the numerous fungi 
from the experimental textile panels, the following 
generalizations were made concerning the fungal flora 
of the samples : 

1. The fungus flora which develops on identical 
samples of fungicidally treated cotton textiles (and 
Nylon) differs widely between sun-exposure and 
shade-exposure conditions. 

2. There is a pronounced difference in the flora 
which develops on textile samples of the same fabric, 
with the same dye and water repellents, but bearing 
diverse fungicides. Hence the composition of the flora 
on treated textiles exposed to tropical conditions for 
even a brief period (ten to twelve weeks) varies not 
only with exposure conditions but also with the chemi- 
cal composition of the fungicide. There are thus two 
variables imposed at the outset on any generalizations 
which may be drawn regarding the nature of the de- 
teriorative organisms on finished textiles exposed to 
tropical conditions. A third, and as yet unpredictable, 
variable resides in the difference between the fungus 
floras of diverse areas in the tropics. 

3. Certain species of fungi capable of attacking 
cellulose have been found on a wide variety of treat- 
ments. These include Botrijodi'plodia theohromcue, 
Penicillium sp., certain Fusaria, Pestalotia, and other 
distinct forms which have not as yet been identified. 

4. There is a tremendous variation both in the num- 
ber of organisms and in the number of species which 
occur on diverse treatments under given conditions of 
exposure. The number and species of the total growth 
is greatest on untreated canvas (i.e., devoid of fungi- 
cide). Of the fungicides tested the compound copper 
8-hydroxyquinoline appeared to have by far the most 
active fungicidal as well as bactericidal effect. As a 
preliminary indication of their potential effect on fab- 


32 


TEXTILE DETERIORATION 


ric, a selected group of 88 species of fungi isolated from 
the textile panels were grown on canvas strips placed 
on niineral-nutrient agar. The luxuriance of growth 
was observed and from this the degree of cellulolytic 
activity was estimated. This procedure of determining 
in a preliminary way the cellulose-digesting capacity 
of a fungus by the amount of hyphal production on 
cotton cellulose is open to some controversy but, in 
general, if an organism is capable of producing a vig- 
orous mycelium on relatively pure cellulose it would 
seem that the cellulose is furnishing a substrate for 
metabolism and growth. Moreover, microscopic ex- 
amination of fibers from certain of the cotton strips 
which supported vigorous hyphal growth showed that 
the cell walls of the cotton hairs were undergoing 
enzymatic attack. Of the 88 forms selected more or 
less at random from a group of 125 isolates, approxi- 
mately 50 species grew with considerable vigor on the 
canvas strips placed on mineral agar. It seems clear 
from this preliminary experiment that an unusually 
large percentage of the fungi isolated from the textile 
panels are capable of degrading cellulose. In this con- 
nection it may be noted that of 450 isolates of fungi 
taken from textile materials sent from the South and 
Southwest Pacific and tested for cellulose deterioration 
at the Philadelphia Quartermaster Corps Tropical 
Deterioration Laboratory, over 50 per cent showed 
significant cellulolytic activity. 

^ ^ Performance of Treatments 

From the data derived by following at intervals the 
tensile-strength measurements made on the experi- 
mental and control panels, and by analyses of the over- 
all conditions of exposure, the relative efficacy of the 
various fabric treatments was determined. The man- 
ner in which the panels were prepared did not justify 
differentiating between the possible causes of the re- 
sults, e.g., the tendering effect (loss of tensile strength) 
of sunlight which was observed may have been more 
])y action of the water repellent than of the fungicide, 
but there is no way to differentiate between these 
causes if both the water repellent and the fungicide 
are present on the same falnlc. 

From these studies it was shown tliat the following 
treatments were satisfactorily resistant to sun-expo- 
sure conditions. 

Copper naphthenate (with screening pigments) 

Copper 8-hydroxyqui noline 

Phenyl mercuritriethanolamine lactate 

Pyridyl mercuric stearate 


Some tendering action 


Permacide plus Para R (phenyl mercury compound) 
Copper ammonium fluoridel 
Pyridyl mercuric chloride J 
There was no statistical basis upon which to eval- 
uate the various treatments under shade-exposure 
conditions. 

The following treatments were satisfactorily resis- 
tant to ground-contact exposure. 

Copper naphthenate and hydroxynaphthenate 
Tetrabrom orthocresol 
CJopper ammonium fluoride 
Copper 8-hydroxyquinoline 

Trimethyloctadecyl ammonium pentachlorophenate 
Pyridyl mercuric stearate 
Pyridyl mercuric chloride 


Phenyl mercuritriethanolamine 
lactate 

Dihydroxydichlorodiphenylmethane 


Unsatisfactory 
on light cotton 
sheeting but 
^ effective on 
shelter-tent 
duck. 


The following treatments were satisfactorily resis- 
tant to soil-burial conditions. 

Copper naphthenate and hydroxynaphthenate 

Chopper 8-hydroxyquinoline 

Pyridyl mercuric chloride 

Pyridyl mercuric stearate 

Copper ammonium fluoride 

Dihydroxydichlorodiplienylmetliane 

Tetrabrom orthocresol 

With due allowances for the variable factors in both 
the application of the treatments and the exposure of 
the test panels, an analysis of the exposure results 
provides a basis for selecting the combinations in the 
above lists which showed the best overall protective 
action. It was concluded that the following combina- 
tions gave the most satisfactory performance in the 
test exposures. 

Copper 8-hydroxyquinoline 
Pyridyl mercuric stearate 

Copper naphthenate (screening pigments essential) 
Pyridyl mercuric chloride 
Copper ammonium fluoride 


^ Conclusions after 16 Weeks 

of Exposure 

Certain salient conclusions derived from this field 
study of experimental textile panels are given as 
follows : 


amnniiiiiiipppii 


FIELD STUDIES IN PANAMA 


33 


1. Climatic conditions during the period of test 
were not severe. Rainfall, particularly during the 
latter part of the rainy season, was not heavy. Exces- 
sive wind movement with attending evaporation ad- 
versely affected the exposure tests and tended to affect 
the effects of high humidity. These considerations ex- 
plain in part the surprisingly slow rate of deterioration 
with ground contact and shade exposure. 

2. Sun exposure brought about greater loss of ten- 
sile strength in the fungicidally treated than in the 
untreated textile panels. Loss of tensile strength with 
sun exposure was particularly high in the case of 
the halogenated phenolic fungicides and the copper 
compounds, particularly copper naphthenate. Samples 
treated with certain water repellents only showed con- 
siderable loss of tensile strength in the sun, indicating 
photochemical breakdown of cellulose by such water 
repellent components as aluminum acetate. 

3. The shade-exposure samples showed no significant 
change in tensile strength after 16 weeks of exposure. 
Visible mold growth appeared first on the sun-exposed 
samples. Of these, mildew was visible on fabric treated 
with tetrabrom orthocresol and Permacide AM-10 
before it was detectable on the untreated controls 
under similar exposure conditions. At the end of lo 
weeks of exposure virtually no mildew was visible on 
any of the treated or untreated shade-exposure panels. 

4. Soil-burial exposure induced rapid deterioration 
of the textile panels although the resistance afforded 
by various treatments differed widely. The perform- 
ance of certain compounds differed very considerably 
depending on the weight of the fabric to which they 
were applied. The compounds wliich gave the best 
protection under the conditions of this test were: 
(1) pyridyl mercuric chloride, (2) copper 8-hydroxy- 
quinoline, and (3) copper naphthenate (solvent ap- 
plication) . 

5. The ground-contact exposures proved to he re- 
tarded soil-burial tests. The results were essentially 
the same qualitatively although quantitatively ground- 
contact conditions were less severe. 

6. Nylon netting proved to be indifferent to soil- 
burial conditions, to ground contact, and to shade 
exposure. Marked loss of tensile strength occurred, 
however, with sun exposure during the latter part of 
the testing period. 

7. On the sun- and shade-exposure samples, pH 
measurements showed a more or less consistent decline 
between the fourth and tenth weeks. In general, pH 
readings were considerably lower in the case of the sun- 
exposed fabrics than in the shade-exposed fabrics. 


8. On agar plates inoculated with yarns taken from 
selected panels after ten weeks of exposure to sun and 
shade, the abundance of fungi was highest in the 
case of the control samples, and by far the lowest on 
material treated with copper 8-hydroxyquinoline. 
Yarns from panels treated with copper naphthenate, 
copper ammonium fluoride, and pyridyl mercuric 
chloride were also low in the number of organisms 
present. All the treatments were not studied by tins 
method, so that a complete comparison is not available. 

9. The species of fungi present in abundance on 
the various treatments differed strikingly with the ex- 
posure conditions and with the chemical composition 
of the fungicide. A few treatments, when plated on 
agar, showed almost pure cultures of certain fungi 
which were present in abundance. 

10. The dominant organisms on a large number of 
the treatments were cultured. The dominant fungi oji 
the same fabric differed somewhat between sun and 
shade exposure. The following species of fungi oc- 
curred in the greatest abundance on the treated tex- 
tile panels : Pullularia sp., Botnjodiplodia theohroinae, 
Pestalotia sp., Penicillium sp., and Fusarium sp. 

11. With the exception of the genus Penicillium, 
none of the test organisms were isolated from the 
fabrics after prolonged exposure. 

12. By correlating tensile-strength changes under 
various exposure conditions with the fungicidal ac- 
tion indicated by culture techniques, the following 
fungicides appeared to be the most satisfactory under 
the conditions of the experiment: Copper 8-hydroxy- 
quinoline, pyridyl mercuric stearate, copper naphthe- 
nate (screening pigment essential), pyridyl mercuric 
chloride, and copper ammonium fluoride. 

13. Examination of the various physical and bio- 
logical factors of the tropical environment and their 
complexity and virtual impossibility of simulation 
demonstrate the necessity for further field research 
and testing in order to validate and render more real- 
istic laboratory testing procedure. 

Results after 60 Weeks of Exposure 

During the initial 16 weeks of exposure the per- 
formance of the experimental textile panels was fol- 
lowed closely in order that the major objectives of the 
experiment would be attained. After 16 weeks it was 
not possible to continue the intense study of the tex- 
tiles. However, there remained two complete sets of the 
sun-exposure series and three complete sets of the 
shade-exposure series. It was arranged that these re- 


34 


TEXTILE DETERIORATION 


iiiainiiig samples would also be subjected to tensile- 
strength measurements. For the sun-exposure samples, 
breaking-strength measurements were made at the 
24-week exposure for one set, and for the shade-ex- 
posure samples, breaking-strength measurements were 
taken at 24 weeks and at 30 weeks. No significant 
changes were noted over the results at 16 weeks. It 
was not planned to obtain breaking-strength values 
for the remaining set of sun- and shade-exposure 
samples at any fixed time; instead, these were to be 
allowed to remain on exposure until trial ^^thunib’’ 
tests revealed weakness in the fabric, and whenever a 
fabric was able to be torn by the thumb test it was 
to be harvested and broken. A few of the sun-exposure 
samples were harvested at 28 weeks, 35 weeks, 40 
weeks, 56 weeks, and 60 weeks. Most of the remaining 
shade-exposure sami)les were harvested at 40 weeks. 

After 60 Aveeks of exposure, the samples which had 
been treated with the folloAving materials still retained 
sufficient breaking strength (thumb test) to warrant 
their continued exposure. 

SUN EXFOSUllE 

Heavy Tent Duck 

C-51 Eire-, water-, Aveather-resistant finish — 
no fungicide 

C-52 Copper naphthenate 

C-53 Copper naphthenate and hydroxynaphthenate 
C-54 Control — no fungicide — tAvo-bath Avater 
repellent 

C-56 Phenyl mercuritriethanolaniine lactate 

Light Cotton Sheeting 

6PC Pyridyl mercuric chloride 
10 Phenyl mercuritriethanolamine lactate 

SHADE EXPOSUPiE 
Heavy Tent Duck 
C-52 Copper naphthenate 

C-53 Coi)per naphthenate and hydroxynaphthenate 

C-55 Tetrabrom orthocresol 

C-57 Dihydroxydichlorodiphenylmethane 

C-58 Copper ammonium fluoride 

60 Copper 8-hydroxyquinoline 

Cotton Sheeting 

C-2 Control — no fungicide 
C-3 Control — no fungicide 


4N6 Copper naphthenate applied as emulsion 
4NH Copper naphthenate, copper 
hydroxynaphthenate 

4C Copper naphthenate applied in hydrocarbon 
solvent — Avater repellent. 

C6 Control — no fungicide 
7P Copper ammonium fluoride 
8 Nylon netting, urea formaldehyde finish 
10 Phenyl mercuritriethanolamine lactate 
lOX Phenyl mercury salt of 2-niercapto 
benzothiazole 

By comparing these results Avith the conclusions 
derived from the exposure test after 16 Aveeks, it Avill 
be seen that the treatments Avhich shoAA^ed best per- 
formance in the entire period Avere among those AAdiich 
Avere judged satisfactory on the basis of the results 
of 16 Aveeks’ exposure. The fact that more samples 
remained in the shade-exposure series indicates that 
jungle shade does not impose conditions as severe as 
those in sun exposure. This contrast is probably pri- 
marily due to the reduced effect of sunlight. Among 
the compounds Avhich gave the best protection in the 
shade-exposure series are copper naphthenate and 
copper hydroxynaphthenate. This applies to the light 
cotton sheeting as Avell as the heavy tent duck. The 
light sheeting samples Avith copper naphthenate treat- 
ment Avere harvested from sun exposure at the 28- 
Aveek period. In contrast, these samples still remained 
on shade exposure after 60 Aveeks. IIoAv^ever, the copper- 
naphthenate-treated heavy tent duck still retained con- 
siderable breaking strength after 60 AA^eeks’ sun ex- 
posure. On the light cotton these treatments Avere 
applied Avithout the screening pigments AAdiich Avere 
applied Avith them on the heavy tent duck. These re- 
sults strengthen and confirm the indications, AAdiich 
Avere apparent after 16 AA^eeks’ exposure, that fabric 
deterioration under field conditions can result from 
the action of sunlight on the fungicide or some other 
ingredient of the finish, thereby bringing about chem- 
ical deterioration of the cellulose itself. 

Additional Exposures 

The Office of the Quartermaster General arranged 
to have a duplicate series of these experimental tex- 
tile panels exposed in Florida asAA^ell as in NeAv Guinea. 
It Avas not possible to folloAV^ the results of each of these 
exposures as closely as the exposures in Panama ; con- 
sequently, the results cannot be analyzed as thorough- 
ly. It can be said, lioAveA’er, that the general perform- 
ance of the individual protective treatments, in the 


4.4.7 


ma 


n 


BACTERIA AND DETERIORATION OF TEXTILES 


35 


case of these two additional exposures, closely paral- 
leled the performance in the Ihinama test. The data 
which are available on these two additional exposures 
are being evaluated and compared with the results of 
the exposures in Panama. 

The Office of the Quartermaster General desired 
to extend the field testing program which was under- 
taken by TDAC after the completion of the original 
test in Panama. One phase of the Quartermaster 
program involved a repetition of the exposure of the 
original textile panels but under conditions which 
more closely approximated actual service conditions. 
The results are now being finally studied but from 
early indications the performance of the various pre- 
ventive treatments again closely paralleled the results 
of the original exposures. An objective of the later 
Quartermaster exposures was to determine more pre- 
cisely the role of the individual components of the 
finish applied to fabrics and to gain a more extensive 
knowledge of the biological deterioration of fabrics. 
For this purpose a more extensive set of experimental 
textile panels was prepared and the exposure condi- 
tions to which these samples were subjected were mod- 
ified in the light of knowledge gained from the orig- 
inal exposures. The results of this phase of the pro- 
gram are also currently being studied and analyzed. 

4.5 RELATIONSHIP OF BACTERIA TO 
DETERIORATION OF TEXTILES 

Investigations to determine the significance of bac- 
teria in the tropical deterioration of textiles were also 
conducted by the Panama Science Mission. These 
field studies were made over a period of about eight 
weeks in contrast to the longer duration of the studies 
on fungi which are discussed above. 

The results of these studies on bacteria are given 
in OSED Report 4806,® which is the basis for the 
summary given in the following sections. The bacteria 
which were isolated during the course of these inves- 
tigations were the nucleus of the Bacteria Culture 
Collection [BCC] which was established to identify 
the organisms and to preserve them for future study. 

Identifications of the bacteria which were made by 
BCC are reported in OSED Report 5682® and are 
discussed in Section 2.3. 

4.5.1 Frequency of Bacteria on 

Exposed Fabrics 

A quantitative estimate of bacteria present on de- 
teriorating samples was considered important in draw- 


ing conclusions regarding the importance of bacteria 
in the deterioration 2 )rocess. For many reasons it was 
necessary to restrict these quantitative studies to only 
a few samples of the treated textiles which are enu- 
merated in Section 4.4.1. These samples on which the 
quantitative studies were made, as well as those other 
samples from which bacteria were isolated, are indi- 
cated in OSED Report 4806.® 

Cellulose-Decomposing Bacteiua 

Twelve samples of tents and tarpaulins in use in 
the Canal Zone were studied for the presence of cel- 
lulose-decomposing bacteria, and from the majority 
of these samples (nine definitely, two probably) such 
bacteria were isolated. In general, the abundance of 
these bacteria appeared to be directly correlated with 
the degree of deterioration of the samples. 

Studies on the treated experimental panels revealed 
that after a short period of exposure to soil contact, 
bacteria were present in large numbers on fabrics to 
which no fungicide or water repellent was added. On 
the fabrics tested which had been given either or both 
of these treatments the bacterial numbers were at a 
low level. Tests on a few fabrics after four weeks’ air 
exposure indicated that bacteria were present on all 
samples. Samples which had been given sun exposure 
contained in general less than 100 bacteria per gram 
of fabric while samples which had been given shade 
exposure showed as many as 1,000 bacteria per gram 
of fabric. 

A total of 145 isolations of cellulose-decomposing 
bacteria were made from the various samples studied 
in Panama. 

Bacteria Other Than Cellulose- 
Decomposing Forms 

Large numbers of these bacteria were found to be 
present on all samples studied, whether they were 
from tents or tarpaulins in use or from the treated 
experimental fabrics. Table 2 of OSED Report 4806® 
indicates the numbers of bacteria per gram of duck 
which were found on the different experimental tex- 
tiles under different exposures with the use of three 
different culture media for isolation. Numbers range 
from a low of 130 thousand per gram of duck to a 
high of 61 million per gram of duck for samples ex- 
posed in air for periods of four to six weeks. With 
reference to these noncellulose-decomposing bacteria, 
fabrics which were protected by a fungicide or water 
repellent, or both, showed far fewer bacteria than fab- 


36 


TEXTILE DETERIORATION 


rics wliich had l)ceii given no preventive treatments. 
In all, a total of 175 isolations of these noncellnlosc- 
deeomposing haeteria were made. 

4 5.2 Significance of Bacteria in 

Fabric Deterioration 

The significanee which cellnlose-decomposing bac- 
teria may hold in the deterioration of fabric is obvi- 
ous, and in the Panama field studies these forms were 
present in large numbers on fabrics which showed 
marked deterioration as evaluated by decrease in 
breaking strength. Xoncellnlose-decomposing bacteria 
were present on samples after four or six weeks’ air 
exposure in such large numbers that it seems they 
may play an important part in the initial stage of de- 
terioration of treated fabrics. As a result of this it 
was suggested that these noncellnlose-decomposing 
bacteria may cause destruction of the treating agents 
which are applied to fabrics, thus causing a reduction 
in fungicidal value and possibly increasing chemical 
deterioration of the fal)ric. 

The program of the Tropical Deterioration Research 
Laboratory [TDRL] of the Philadelphia Quarter- 
master Depot which has been summarized in Section 
4.9 included comprehensive studies of bacteria, par- 
ticularly cellnlose-decomposing forms. These studies 
concerned nutritional requirements and optimal con- 
ditions for growth of these organisms in order to gain 
information which would be applicable to test methods 
and which would shed some light on the significance 
of these forms in the deterioration of fabrics niidei* 
natural conditions.^ This work also included tests to 
determine the effectiveness of commercial applications 
of different fungicides on the few l)acteria which were 
studied in detail.® The results indicated that concen- 
trations of fungicides which were inhibitory to fungi 
were also inhibitory to bacteria. The variations be- 
tween the resistance of the bacteria used and a fungus 
used as a check were no greater than those which ordi- 
narily occur between two or more species of fungi in 
regard to their resistance to different fungicides. Some 
of the results of the Panama field studies confirm this 
fact, since bacteria Avere present in feAver numbers on 
fimgicidally treated fabrics than upon those Avhich 
had been given no fungicidal treatment. In spite of 
these results, it seems that because noncellulose-de- 
composing bacteria Avere found on both treated and 
untreated fal)rics in such prodigious numbers, even 
after relatively short exposure periods, further inves- 
tigation of the exact role of these organisms in the 


deterioration of fabrics is Avarranted. These noncel- 
lnlose-decomposing forms include far greater num- 
bers of bacteria and shoAv a much AA'ider range of 
characteristics and properties than do the cellnlose- 
decomposing forms Avhich Avonld be significant prob- 
ably only in the destruction of the fabric itself. If it 
could be shoAAm that these noncellnlose-decomposing 
forms can somehoAV render protective treatments 
ineffective against fungi, the need for protective meas- 
ures against these noncellulose-decomposing bacteria 
AVonld be established. 

4 6 the effect of copper naphthenate 

ON THE DETERIORATION OF 
COTTON FABRIC 

Preliminary evidence indicated that copper naph- 
thenate, the fungicide so Avidely used by the Army and 
Navy on such items as tentage and tarpaulins, may 
itself contribute to a reduction in the tensile strength 
of these fabrics Avhen exposed to sunlight and AA^eather. 
Upon the recommendation of the TDAC Subcommit- 
tee on Textiles and Cordage, cooperative investiga- 
tions to determine Avhether or not commercial copper 
naphthenate accelerates the deterioration of cotton 
AA^ere arranged Avith the National Bureau of Standards 
[NBS]. These studies involved extensive laboratory 
tests and analyses, as Avell as outdoor exposures of 
experimental fabrics under the different climatic 
conditions of Washington, D.C., Dickerson, Maryland, 
NeAv Orleans, Louisiana, and AAinia, Arizona. It AA^as 
not to be expected that an immediate solution of the 
problem Avould be acliieved, but a good start has been 
made, and NBS intends to complete the investigations. 

From an analysis of the data obtained thus far,® the 
folloAving conclusions Avere draAvn ; 

1. The copper naphthenate on the duck accelerated 
its deterioration. 

2 . The gray duck Avas more stable than the copi)er- 
naphthenate-treated duck except AAdiere there is evi- 
dence (fluidity results) of inildeAV action (Ncav Or- 
leans tests). 

3. Loss of copper from the copper-naphthenatc- 
treated duck is attributable not only to leaching by 
rain but to other causes. (There Avas 22 per cent loss 
of copper at Yuma in the first 80 days of exposure 
even though no I’ain fell during that time.) 

4. Local differences in conditions of exposure 
(Washington and Dickerson) may affect the results 
of outdoor Aveathering to as great or greater extent 



THE EFFECT OF LIGHT ON FABRICS 


37 


than geographical dilfereiiccs in climate (Dickerson 
and Yuma). 

An effort was made to prevent or reduce the accel- 
erating action of the copper naphthenate with antioxi- 
dants (pyrogallol, hydroquinine, alphanaphthol) and 
with an inhibitor (phenyl salicylate) but no reduc- 
tion in the rate of deterioration was obtained. 

Some data were obtained on the weathering be- 
havior of copper naphthenate on cloth of different 
weights with and Avithout the addition of a Avax Avater- 
proofing compound, but these still remain to be an- 
alyzed. There also remain to be completed the final 
tests and analj^ses of exposed fabrics AAdiich AA^erc 
treated Avith (1) laboratoiy-prepared copper naph- 
thenate free from copper sulphate, naphthenic acids, 
etc., (2) naphthenic acids, and (3) laboratory-pre- 
pared copper naphthenate plus copper sulphate and 
1 per cent pentachlorophenol. The objective in these 
exposure tests Avas to contrast the performance of 
commercial applications of copper naphthenate, hav- 
ing various impurities present, AAuth the purer labo- 
ratory-prepared compounds. The laboratory acceler- 
ated AA^eathering tests AAdiich Avere performed on this 
series of treated fabrics did not correlate Avith outdoor 
exposures. 

47 EFFECTIVENESS OF COMBINATIONS 
OF FUNGICIDES 

Upon the recommendation of the Subcommittee on 
Textiles and Cordage, cooperative tests Avith NBS 
Avere also undertaken to determine Avhether mixtures 
of fungicides are a satisfactory substitute for fungi- 
cides in limited supply, and to extend the usefulness 
of fungicides Avhich are good rot resisters but Avhich 
afford little protection against surface growing organ- 
isms. As with the investigations on copper naphthe- 
nate, these still remain to be completed, but it is the 
intention of NBS to continue them as a post-Avar 
project. 

It is indicated in a brief summary Avhich has been 
made of this work® that in these investigations nearly 
all the available fungicides and mixtures of some of 
them Avere rated Avith respect to fungicidal efficiency 
AA^hen applied to cotton cloth in a series of concentra- 
tions. The evaluation tests employed Avere pure-culture 
tests using the organisms Chaetomium glohosum and 
Aspergillus niger. The treated fabrics were tested 
^‘as is” and after exposure to leaching and laboratory 
AA^eathering. 


Cloths containing over 0.5 per cent copper in the 
form of copper naphthenate and cloths containing 
over 1.0 per cent of pyridyl mercuric stearate Avere 
rated excellent in all the tests AAdiether the fungicides 
Avere used singly or in mixtures Avith other fungicides. 

Experimental cloths Avhich contained the folloAving 
fungicides in amounts above those noted were rated 
excellent Avhen tested ^"as is” but were giA^en a lower 
rating after one or more of the exposure treatments. 


Copper phenyl naphthenate 

0.1% Cu 

Dihydroxydichlorodiphenylmethane 

Copper oleate 0.6% Cu and 

1.0% 

dihydroxydichlorodiphenylmethane 

Copper phenyl naphthenate 0.2% Cu and 

1.2% 

dihydroxydichlorodiphenylmethane 

Phenyl naphthenate 0.2% Cu and pyridyl 

0.9% 

mercuric stearate 

0.2% 

Zinc phenyl naphthenate 

1.0% Zn 

Hyamine 3258 

1.0% 

Copper phenyl oleate 

0.2% Cu 

and dihydroxydichlorodiphenylinethane 

1.0% 

Phenyl mercuric acetate 

0.5% 

Tetrabrom orthocresol 

0.5% 

Puratized MC 

1.5% 

Puratized FL 

1.0% 

Pentachlorophenol 

1.0% 


Cloths containing fungicides reported beloAv Avere 
rated poor in all tests. 

Copper phenyl oleate 
Copper oleate 
Copper tannate 
Copper tallate 
Creosote 

Copper phenyl oleate and creosote 
Copper hydroxynaphthenate 
Copper acetate and creosote 
Methylene disalicylic acid 
Bis-phenol A 
Phenyl salicylate 
Copper stearate 
Zinc phenyl oleate 
Naphthenic acid 

In the Avork Avhich has been completed, mixtures of 
fungicides have not proved to be superior to equivalent 
amounts of the components AAdien used alone. 

4 8 the EFFECT OF LIGHT ON FABRICS 

The problem of the effect of light on fabrics occu- 
pied the attention of the Subcommittee on Textiles 
and Cordage to a considerable degree and all available 
information on the subject Avas summarized for this 
group. Certain aspects of the problem Avere directly 
related to these studies on copper naphthenate and 
combinations of fungicides Avhich are cited above. The 
results of the Panama field exposures, AAdiich indicated 


38 


TEXTILE DETERIORATION 


that in sunlight exposure fungicidally treated fabrics 
performed less satisfactorily than controls which were 
given no fungicidal treatment, emphasized the impor- 
tance of studies on the action of light. The desirability 
of inaugurating separate studies on this subject was 
considered but because of the long-range nature of 
these studies and the difficulty in selecting a suitably 
qualified institution for conducting them, as well as 
the late stage of World War II, it was decided not to 
attempt to organize these studies under a separate 
project, but to incorporate as many aspects of the 
problem as possible with those investigations whicli 
were being conducted at NBS. 

Valuable fundamental information on the action 
of sunlight on cotton cellulose has resulted from in- 
vestigations sponsored by the Office of the Quarter- 
master General.^® The adverse effect of light on the 
tensile strength of cotton fabrics has been recognized, 
and these investigations confirm this fact as well as 
the fact that it is the ultraviolet portion of the spec- 
trum, rather than the visible portion, which is respon- 
sible for the effect. The evidence indicates the occur- 
rence of a photochemical reaction which is independ- 
ent of oxygen concentration and humidity, but affected 
by temperature, and results in an alteration of the 
cellulose. The products of the photochemical reaction 
are capable of oxidation, giving rise to oxycellulose. 
This ultraviolet modified cellulose has been shown to 
be more resistant to attack by the test fungus, Metar- 
rhizium, than untreated controls. This may be ac- 
counted for on the basis that the modified cellulose 
possesses a substrate which affects the fungal growth 
and is supported by studies which demonstrated that 
oxidized cellulose derivatives are fungus resistant. 
However, the increased resistance to fungus attack is 
not considered to outweigh the harmful elfects of 
ultraviolet light.^® 

The results of this work are regarded as important 
supplementary information to other studies on the 
deterioration of cellulose by microorganisms, and fur- 
nish a basis for the reported field observations on the 
mildew-resistance of exposed tents. The results also 
have a distinct bearing on the problem of photochem- 
ical deterioration of treated fabrics as was observed 
in the Panama field tests. 

4 9 the QUARTERMASTER PROGRAM ON 
THE DETERIORATION OF TEXTILES 

In addition to the practical approach centering 
around process development and evaluation techniques 


for mildew-resistant treatments of textiles, the Quar- 
termaster Corps organized TDRL in July 1944 at the 
Philadelphia (Quartermaster Depot to extend the fun- 
damental knowledge of the microorganisms encoun- 
tered in the processes by which damage of textiles is 
brought about. The exploratory and ex])erimental pro- 
gram of this laboratory has been direeted toward 
development of the scientific background which is 
essential before further advances in the prevention of 
textile deterioration can be made. 

The program of TDRL has furnished signiheant 
fundamental information on many phases of cellulose 
deterioration on which little or no information pre- 
viously existed. A recent report outlined the progress 
which has been made to date on aspects of the micro- 
biological degradation of cotton fabrics, the mecha- 
nism of degradation of cellulose, and methods of pre- 
vention of microbiological degradation.® 

The work on the causal biological agents has l)een 
related to that of TFCC and BCC, which are discussed 
in Chapter 2. Whereas the bulk of organisms in 
TFCC were derived from Panama studies, the major- 
ity of organisms isolated under the Quartermaster 
program were derived from deteriorated military 
equipment returned from Pacific areas. In addition 
to the isolation and identification of these organisms 
their cellulolytic activity was determined, particularly 
for the fungi. In this work the Quartermaster Labo- 
ratory and TFCC cooperated closely. 

Studies on the mechanism of degradation of cellu- 
lose involved investigations for determining the op- 
timum condition for the groAvth of microorganisms, 
particularly those to be used for test purposes. In ad- 
dition, comprehensive studies were made on the nutri- 
tional and environmental requirements of cellulolytic 
bacteria and fungi, and the effect which the environ- 
ment exerts on the resistance of fabrics to microbio- 
logical attack. (See Section 4.8 for the etfect of light.) 
Investigations were also undertaken to determine the 
chain of reactions which occur in the degradation of 
cellulose; these involve determining the relationship 
between molecular structure and microbiological re- 
sistance, the effects of enzymes, and other studies per- 
taining to the utilization of cellulose by microorgan- 
isms. 

Attention has been directed to certain restricted as- 
pects of methods for the prevention of microbiological 
degradation of fabrics. Methods involving cell toxicants 
(fungicides) or specific enzyme inhibitors have been 
studied only with respect to certain fundamental con- 
siderations. The impregnation of fabrics with micro- 


QUARTERMASTER PROGRAM 


39 


biological-resistant resins has given encouraging re- 
sults and the potentialities of such treatments arc rec- 
ognized. Considerable initial success has been experi- 
enced in the attempt to impart mildew resistance to 
fabrics by affecting a chemical modification of the 
cellulose itself. Test fabrics given a wide variety of 
chemical treatments in which a chemical combination 
between the cellulose and treating agent was probable 
showed complete fungus resistance when evaluated by 
a standard procurement test. The possibilities which 


this approach offers arc being explored further. On 
the basis of these early results, chemical modification 
of cellulose may prove to be the most feasible approach 
to attaining a superior degree of mildew resistance in 
fabrics. 

It will be noted that these investigations which have 
occupied the attention of the Quartermaster Corps 
are closely allied to those aspects of the problem which 
have been recommended for future investigations in 
Chapter 10. 


t 


Chapter 5 

THE PROBLEM OF FUNGAL GROWTH ON SYNTHETIC 
RESINS, PLASTICS, AND PLASTICIZERS^ 

By Alfred E, Hround^ 


51 INTRODUCTION 

A SEARCH OF THE SCIENTIFIC literature through 
1944 reveals many references relating to the de- 
terioration of textiles, leather, paints, metals, and 
wood products by moisture and fungi, as well as 
treatments devised to protect these materials, but not 
one publication dealing directly with the tropical de- 
terioration of plastics or their components.® 

This paucity of information is by no means unex- 
pected because, prior to AVorld IVar II, plastics were 
not giving any serious trouble of this nature in the 
temperate zones where they were most used. However, 
since 1942 the Armed Forces of the U. S. as well as 
those of Britain, Canada, and Australia, have moved 
large quantities of equipment into tropical areas. 

The deterioration of textiles by microorganisms 
under tropical conditions is easily demonstrated and 
has been definitely accepted. As yet no such agree- 
ment exists in regard to many types of plastic mate- 
rials. Because of the recent origin of this problem, as 
well as the ratlier limited investigations that could 
be carried on in wartime, insufficient data have led to 
differences of opinions regarding rather fundamental 
questions. For example, in some cases conclusive evi- 
dence that microorganisms grow oii the plastic itself, 
rather than on surface contaminants like dust and 
fingermarks, has not yet been obtained. This is due 
to the fact that no effective treatment for cleaning 
plastics without removing lubricants, etc., has been 
forthcoming, and as a result, most plastics are tested 


as received. Also, even though fungi do grow on nu- 
trients supplied by some plastic materials, there is 
considerable doubt as to whether either the properties 
or the composition of the materials have actually been 
altered. An even more controversial question, especial- 
ly with reference to the performance of plastics in 
electric equipment, is whether fungi and moisture 
actually cause a greater deleterious effect on electric 
properties of plastics than moisture alone under the 
same conditions. 

The NDRC Tropical Deterioration Administrative 
Committee [TDAC] established in July 1944 a Sub- 
committee on Synthetic Resins, Plastics, and Plas- 
ticizers to consider the problems of tropical deteriora- 
tion of these materials. 

52 SUSCEPTIBILITY OF PURE RESINS 
TO FUNGAL ATTACK 

The major component of almost all plastic mate- 
rials is the polymer itself. For this reason a study of 
the fungal susceptibility of the resin without added 
plasticizer, lubricant, and any other component is 
important. Table 1 lists the results obtained for rep- 
resentative materials by different laboratories. 

K glance at the results shows why synthetic resins 
in general have earned the reputation of being resist- 
ant to fungus. The term resistant is used only to de- 
note that the material does not serve as a source of 
carbon for the growth of fungi. Aside from the slight 
susceptibility of cellulose nitrate, polyvinyl acetate, 
and melamine-formaldehyde polymers, synthetic resins 
are indeed resistant to fungal growth. However, al- 
though the resins themselves do not support such 
growth, it must be remembered that neither do they 
inhibit it. 

In view of the marked resistance of pure resins to 
fungal attack, it can be assumed that when plastic 
materials support growth, the addition of other com- 
ponents is most likely responsible for it. Such a hy- 


'‘Abridged from OSRD Rei)ort 6067^ of same title. Details 
regarding the test methods used to determine fungal resistance 
and a recommended test procedure, given in the original 
report, are omitted here and discussed in Chapter 8. The 
subject as discussed here represents a general review of the 
problem and includes information ])resented in OSRD Report 
5683.2 This chapter has been approved for publication in 
Modern PlaMics by the OSRD Committee on Publications, 
and the original text is used except for changes in format. 

•’Research Associate, TDAC Subcommittee on Synthetic 
Resins, Plastics, and Plasticizers. 

•^Two articles of a general nature have recently appeared.^*’^^ 


40 


SUSCEPTIBILITY OF PLASTICIZERS AND OTHER COMPONENTS 


41 


pothesis augers well for the future, since, as test re- 
sults indicate which ingredients other than resins are 
fungus-resistant, the addition of such components may 
give rise to fungus-resistant plastics. 


Table 1. Fungal resistance of pure synthetic resins.* 


Substance 

Extent of 
growth t 

Laboratory f 

Thermoplastic materials 

Cellulose acetate 

B,A,A 

1,2,5 

Cellulose acetate butyrate 

A, A 

1,5 

Cellulose acetate propionate 

A 

1 

Cellulose nitrate 

C 

1 

Ethyl cellulose 

A, A 

1,5 

Polyethylene 

A, A 

1,2 

Polymethylmethacrylate 

A, A, A 

1,2,5 

Polystyrene 

A, A, A 

1,2,5 

Polydichlorostyrene 

A 

5 

Polyvinyl acetate 

C,A 

1,5 

Polyvinyl butyral XYSG 

A 

3 

Polyvinyl chloride 

A, A 

1,2 

Polyvinyl chloride acetate VYNW 

A, A 

1,3 

Polyvinyl chloride acetate VYNS 

A 

3 

Thermosetting materials 

Phenol-aniline-formaldehyde 

A,B 

4,5 

Phenol-formaldehyde 

A,B 

3,5 

Melamine-formaldehyde 

C,B 

1,5 

U rea-f ormaldehy de 

A, A 

1,2 


*Where the same resin had been tested in different laboratories, all the 
results are given to indicate the divergence of opinion on ratings. These 
ratings are listed under “Extent of Growth” with the sources listed in the 
same order under "Laboratory”; thus, for cellulose acetate, B,A,A under 
“Extent of Growth” followed by 1,2,5 under “Laboratory” means that 
NBS (1) rated the material B, British Ministry of Supply (2) rated the 
material A, and the General Electric Co. (5) rated the material A. 
fCode: A no growth; B very slight or light growth; C moderate growth. 
JCode: 1 National Bureau of Standards;* 2 British Ministry of Supply;^ 
3 Boyce Thompson Institute;* 4 Naval Research Laboratory;* 

5 General Electric Company.® 


5 3 SUSCEPTIBILITY OF PLASTICIZERS 
AND OTHER COMPONENTS TO 
FUNGAL ATTACK 

Components other than the pure resin constitute 
an important portion of a plastic material. In lami- 
nated thermosetting materials the ply is usually a 
cellulose material like linen, canvas, or paper, or an 
inorganic material like woven glass or asbestos. The 
susceptibility of the former, as well as the inertness 
of the latter, to fungal attack is well known. With 
molded thermosetting materials, the filler is usually 
a cellulosic material such as some type of wood flour, 
cut cotton cloth, or an inorganic material like asbestos 
fiber or mica. Here again the behavior of these mate- 
rials to fungal attack is well known. That all wood 
flours are not equally susceptible has recently been 


demonstrated by the Boyce Thompson Institute.^ 
Wood flock and walnut-shell flour proved more sus- 
ceptible than soft-wood flour. 

The situation with regard to thermoplastic mate- 
rials is different. In these materials a wide variety of 
plasticizers is used. Many hundreds of compounds 
have been tried as plasticizers and some 150 materials 
which are presently in use are listed in the Plasticiz- 
ers Chart of the Plastics Catalog^ Since all organic 
materials cannot be utilized to the same extent as a 
source of carbon by all fungi, it is to be expected that 
some plasticizers will be more resistant than others. 

The data obtained for the susceptibility of plasticiz- 
ers to fungal attack are presented in Table 2. The 
compounds are listed in the same order as found in 
the Plasticizers Chart; three general classes. Oils, 
Resin Plasticizers, and Miscellaneous, have been added. 

These data can be used as a guide in the selection 
of resistant materials for plastic formulations. In 
many cases where a number of plasticizers can serve 
equally in imparting the required properties, one that 
is rated A or B would be preferred if greater fungal 
resistance is desired in the plastic. Including a plas- 
ticizer rated D in a formulation would render a plas- 
tic susceptible to attack. It is for this first purpose 
that all the specific plasticizers have been listed so that 
this information may receive the widest circulation. 

In the pharmaceutical and nutritional fields, the 
relationship between physiological activity and chem- 
ical structure receives a good deal of study. In this 
manner, the importance of certain functional groups 
is discovered, and tailor-made molecules are synthe- 
sized for special purposes. The success of this method 
in the sulfa drug field is well known. Since the nutri- 
tional availability of various substrates to fungi is also 
a physiological function dependent probably on enzyme 
systems, in spite of the numerous genera of fungi in- 
volved, some correlation with structure should be ap- 
parent from a study of a sufficient number of com- 
pounds. 

Study of the data with this latter purpose in mind 
leads to a number of conclusions. The striking sus- 
ceptibility of fatty acid derivatives is easily discerned. 
Thus, all derivatives of 1 auric, oleic, ricinoleic, and 
stearic acids are attacked. In addition, natural oils 
like castor and cottonseed containing glyceryl esters 
of these acids are susceptible. 

A sufficient number of aliphatic dicarboxylic acid 
derivatives have not as yet been tested, but the data 
available show that whereas succinic and adipic acid 
derivatives are resistant, the sebacic acid derivatives 


42 


SYNTHETIC RESINS, PLASTICS, AND PLASTICIZERS 


Table 2. Fungal susceptibility of various plasticizers.* 

Extent of 

Name Trade name growth f Laboratory J 


Abietic acid derivatives 
Abietic acid 

Hydrogenated methyl abietate 
Aconitic acid derivatives 
Tri-n-butyl aconitate 
Triethyl aconitate 
Adipic acid derivatives 

Di-( 1,3-dimethyl butyl) adipate 
Di-(2-ethylhexyl) adipate 
Azelaic acid derivatives 

Di- (ethylene glycol monobutyl ether) azelate 
Di-(2-ethylhexyl) azelate 
Benzoic acid derivatives 
Ethyl-o-benzoyl benzoate 
Benzyl benzoate 
Chlorinated hydrocarbons 
Mixtures of 

chlorinated diphenyls 
chlorinated diphenyls 
chlorinated diphenyls 
chlorinated diphenyls 
chlorinated diphenyls 
chlorinated diphenyls 
chlorinated diphenyls 
Chlorinated paraffin 
Chlorinated paraffin 
Citric acid derivatives 
Tri-n-butyl citrate 
Triethyl citrate 
Glycerol derivatives 
Glyceryl triacetate 
Glycol derivatives 

Diethylene glycol ethyl ether acetate 

Diethylene glycol butyl ether acetate 

Diacetate of 2-nitro-2-methy 1-1, 3-propanediol 

Dijn-opionate of 2-nit ro-2-methyl- 1,3-propanediol 

Diethylene glycol dipropionate 

'^J'riethylene glycol di-(2-ethylhexoate) 

Triethylene glycol di-(2-ethylbutyrate) 

Polyethylene glycol 200 

Polyethylene glycol 300 

Polyethylene glycol 400 

Polyethylene glycol 1500 

Polyethylene glycol 6000 

Polyethylene glycol di- (2-ethyl hexoate) 

Glycolic acid derivatives 

Ethyl phthalyl ethyl glycolate 
Methyl phthalyl ethyl glycolate 
Methyl phthalyl methyl glycolate 
Butyl phthalyl butyl glycolate 
Laurie acid derivatives 
Butyl laurate 
Ethylene glycol laurate 
Ethylene glycol ethyl ether laurate 
Diethylene glycol monolaurate 
Diethylene glycol ethyl ether laurate 
Glyceryl laurate 
Sorbitol laurate 


A 

Hercolyn A,B 

C,A 

B.A 

B 

A 


Dibutyl Cellosolve azelate B 

A 

Ketonone E A 

C 


Arochlor 1242 A 

Arochlor 1248 A 

Arochlor 1254 B 

Arochlor 1262 A 

Arochlor 1263 B 

Arochlor 1270 A 

Arochlor 5460 A 

Chlorowax A 

Cerechlor A 


A,A 

A 


Triacetin C,C 

Carbitol acetate C,B 

Butyl Carbitol acetate B 

A 

A 

KP-45 A 

Flexol 3GO A, A, A 

Flexol 3GH A,A,A 

A 

A 

A 

Garbo wax 1500 A 

Carbowax 6000 A 

Flexol 4GO A 

Santicizer E-15 C 

Santicizer M-17 B 

B 

Santicizer B-16 C,C,A 

D 

D 

Cellosolve laurate D 

D 

Carbitol laurate D 

D 

D 


4 

1,4 

1,4 

1,4 

4 

4 

4 

4 

1 

1 


4 

4 

4 

4 

4 

4 

4 

4 


1.4 
1 

1.4 

1.4 
4 

1 

1 

1 

1.3.4 
1,3,4 
4 

4 

4 

4 

4 

1 

1 

1 

4 

1,3,4 

4 

4 

4 

4 

4 

4 

4 


♦Where the same plasticizer has been tested in different laboratories, all the results obtained are listed under “Extent of Growth” with the sources 
listed in the same order under “Laboratory.” 

tCode: A no growth; R very slight, or light growth; C moderate growth; D heavy and very heavy growth. 

jCode; 1 National Bureau of .Standards;* 2 British Ministry of Supply .3 Boyce Thompson In-stitute;* 4 Naval Research Laboratory.* 


SUSCEPTIBILITY OF PLASTICIZERS AND OTHER COMPONENTS 


43 


Table 2. Fungal susceptibility of various plasticizers (continued). 


Extent of 

Name Trade name growth f Laboratory J 


Oleic acid derivatives 

Dibutyl ammonium oleate D 4 

Ethylene glycol methyl ether oleate Methyl Cellosolve oleate C 1 

Nitrile from oleic and linoleic acids NTD-181.5-B D 3 

Sorbitol oleate D 4 

Pentaerythritol derivatives 

Dipentaerythritol hexaacetate A 1 

Dipentaerythritol hexapropionate B 1 

Dipentaerythritol hexabutyrate A 1 

Pentaerythritol diacetate-dibutyrate C 1 

Pentaerythritol diacetate-dipropionate C 1 

Pentaerythritol monoacetate-tripropionate B 1 

Pentaerythritol triacetate-monopropionate C 1 

Pentaerythritol tripropionate-monomyristate C 1 

Pentaerythritol tetrabutyrate C 1 

Pentaerythritol tetrapropionate C 1 

Phosphoric acid derivatives 

Triethyl phosphate A 1 

Tributyl phosphate A, A 1,4 

Tri-(2-ethylhexyl) phosphate Trioctylphosphate A 3 

Triphenyl phosphate A 1 

Tributoxyethyl phosphate Tributyl Cellosolve phosphate A 4 

Tricresyl phosphate Kronitex AA A, A, A, A 1,2, 3, 4 

Tri-(2-nitro-2-methylpropyl) phosphate A 1 

Diphenyl mono-(p-tert.-butylphenyl) phosphate Dow Plasticizer 1 B 4 

Monophenyl di-(p-tert.-butylphenyl) phosphate Dow Plasticizer 2 A 1 

Diphenyl mono-(o-chlorophenyl) phosphate Dow Plasticizer 3 A 4 

Diphenyl mono-o-xenyl phosphate Dow Plasticizer 5 A,B 1,4 

Di-o-xenyl monophenyl phosphate Dow Plasticizer 6 A, A 1,4 

Tri-(p-tert.-butylphenyl) phosphate Dow Plasticizer 7 A,A 1,3 

Tri-(o-chlorophenyl) phosphate Dow Plasticizer 8 A 4 

Tri-(o-xenyl) phosphate Dow Plasticizer 9 A 1 

Phthalic acid derivatives 

Dimethyl phthalate A 1 

Diethyl phthalate A, A 1,4 

Di-/i-propyl phthaltate A 1 

Di-isopropyl phthalate A 1 

Dibutyl phthalate A, A, A 1,2,4 

Di-isobutyl phthalate A 1 

Diamyl phthalate C 1 

Dihexyl phthalate A 2 

Dicap ryl phthalate A,B 1,4 

Dioctyl phthalate A 1 

Di-(2-ethylhexyl) phthalate Flexol DOP, Dioctyl phthalate A,A,A 1,3,4 

Dicyclohexyl phthalate A 1 

Dibenzyl phthalate A,B, 1,4 

Diphenyl phthalate B 4 

Dimethoxyethyl phthalate Dimethyl Cellosolve phthalate; Methox A 1 

Diethoxyethyl phthalate Di-Cellosolve phthalate; Ethox A 1 

Dibutoxyethyl phthalate Dibutyl Cellosolve phthalate; Kronisol A, A 1,3 

Methyl-2-methyl-2-nitro-propyl phthalate A 1 

Ethyl-2-methyl-2-nitro-propyl phthalate B 1 

Butyl-2-methyl-2-nitro-propyl phthalate A 1 

Bis- (diethylene glycol ethyl ether) phthalate Di-Carbitol phthalate A 1 

Resin plasticizers 

Glycol sebacate resin Paraplex D 1 

Sebacic acid alkyd resin Paraplex G-25 D,C 1,3 

Sebacic acid alkyd resin Paraplex RG-2 D 1 

Sebacic acid alkyd resin Paraplex RG-20 D 1 

Sebacic acid alkyd resin Paraplex X-100 D 3 

Ester type alkyd resin Duraplex C50LV D 4 

Silicone oil Fluid #500 A 4 


44 


SYNTHETIC RESINS, PLASTICS, AND PLASTICIZERS 


Table 2. Fungal susceptibility of various plasticizers (continued). 


Extent of 


Name Trade name growth f Laboratory t 


Ricinoleic acid derivatives 

Methyl acetyl ricinoleate P-4 D 3 

Butyl acetyl ricinoleate D 1 

Ethylene glycol methyl ether acetyl ricinoleate Methyl Cellosolve acetyl ricinoleate C 1 

Glyceryl monoricinoleate D 4 

Sebacic acid derivatives 

Dimethyl sebacate C 1 

Di butyl sebacate C,C 1,4 

Di-( 1,3-dimethyl butyl) sebacate B 4 

Di-(2-ethylhexyl) sebacate Dioctyl sebacate C 4 

Stearic acid derivatives 

Stearic acid D 3 

w-Butyl stearate C 1 

Cyclohexyl stearate D 1 

Butoxyethyl stearate Butyl Cellosolve stearate D,D 1,4 

Diethylene glycol ethyl ether stearate Carbitol stearate D 4 

Tetraethylene glycol monostearate D 4 

Tetraethylene glycol distearate D 4 

Succinic acid derivatives 

Diethyl succinate A 4 

Synthetic fatty acid derivative 

Fatty acid dimethyl amide Plasticizer 35 D 4 

Tartaric acid derivative 

Di-n-butyl tartrate A 1 

Toluenesulfonic acid derivatives 

Ethyl-p-toluenesulfonate A 1 

o-Cresyl-p-toluenesulfonate Santicizer 10 A 1 

0 - and p-Toluene ethylsulfonamide Santicizer 8 A 1 

Tricarballylic acid derivatives 

Triethyl tricarballylate B 1 

Tri-n-butyl tricarballylate B 1 

Oils — natural and synthetic 

Tung oil B 4 

Castor oil D,D,D 1,3,4 

Cottonseed oil D 4 

Dehydrated castor oil Isoline D 3 

Refined tall oil Indusoil D 3 

Sulfonated oil Naftolen R-510 A 4 

Coal tar oil A 4 

Petroleum oil A 4 

Miscellaneous materials 

Diphenyl A 1 

Diamylnaphthalene A, A 1,4 

Diamylphenoxyethanol A 4 

Benzophenone A 4 

Methylamyldihexylcyclohexanone Plasticizer C-24 A 4 

Cyclohexyl lactate A 1 

Methylcyclohexyl oxalate A 1 

Diphenylsulphone A 1 

Triphenylguanidine A 1 

Triethanolamine dicaprylate Plasticizer SC D 4 


are susceptible. Thus, in this series also, a long carbon 
chain of ten atoms or more renders the derivative sus- 
ceptible. The three aliphatic tricarboxylic acid deriva- 
tives listed, those of citric, aconitic, and tricarballylic 
acids, are seen to be resistant. 

As long as the glycol and glycolic acid derivatives 
do not contain any aliphatic acids having chains of 
ten or more carbon atoms, the results show them to be 


resistant to fungal attack. Pentaerythritol esters are 
found to be fair to good in resistance. 

The results obtained with the phthalic acid deriva- 
tives, many of which enjoy wide use, are consistent, 
and conclusively show that these derivatives are very 
resistant to fungal attack. Thus, the aliphatic esters 
ranging from dimethyl to dioctyl phthalate, and in- 
cluding the ester of the cyclic alcohol, cyclohexanol, 


SUSCEPTIBILITY OF PLASTIC COMPOSITIONS 


45 


as well as the Cellosolve and Carbitol esters are all 
resistant. The phenyl and benzyl esters are also re- 
sistant. The phosphoric acid derivatives show a sim- 
ilar behavior. All the aliphatic and aromatic esters 
listed are resistant to fungal attack. 

The resistance of the tolnenesulfonic acid deriva- 
tives, as well as the resistance of the aromatic hydro- 
carbons, is also obvious. The only terpene derivatives 
investigated, those of abietic acid, were also found 
resistant. 

Although the choice of both a resistant resin and a 
resistant plasticizer in a plastic are indicated, on the 
basis of present knowledge, it cannot be said that be- 
cause components A and B are resistant, the com- 
bination of A and B is resistant. Experiments show 
that combinations of dioctyl phthalate with vinyl 
resins are more susceptible than either alone. How- 
ever, the presence of small quantities of lubricant must 
be considered for it has been shown that the plasticizer- 
lubricant combination is more susceptible than either 
one alone. 

Further investigation on mixtures of components 
such as resins, lubricants, and plasticizers should cast 
more light on these problems. However, it is generally 
acknowledged at the present time that the fungal re- 
sistance of a plastic can be estimated with some cer- 
tainty if the susceptibility of the components which 
go to make it up is known. It is for this reason that 
data on plastics components are so valuable. 

54 SUSCEPTIBILITY OF PLASTIC COM- 
POSITIONS TO FUNGAL ATTACK 

Included in the vast array of items termed military 
materiel one finds many examples of plastics. Thus, 
items as varied as molded gun stocks, gun covers, air- 
craft windows, terminal boards in radio sets, machete 
sheaths, helmets, and belly tanks may be included. 
The resins on which these materials are based may 
indeed be similar, but the complete compositions of 
the final articles are often different. In this sense 
terminal boards are not merely phenol-formaldehyde 
resins, nor are gun covers merely polyvinyl chloride 
acetate resins. The terminal board ordinarily contains 
plies of fabric, or paper if it has been prepared from 
laminated stock, or it has filler added if it is a molded 
piece. In the same manner the vinyl esters have added 
plasticizers, lubricants, and stabilizers. If it is con- 
stantly kept in mind that commercial plastics as we 
know them are complex mixtures, the conflicting re- 
ports concerning tropical deterioration of certain plas- 


tics become more understandable. A polyvinyl chloride 
acetate insulation covering is not the same material as 
a polyvinyl chloride acetate coating on a raincoat, 
nor is a phenolic gun handle the same material as a 
phenolic tube socket. 

Being aware of the fact that a plastic is a mixture 
of components, one might think that the first step 
would be to check all the components of plastics for 
fungal susceptibility and then make the plastics from 
resistant components. This approach is sound and 
has great merit. However, when plastic materials per- 
formed unsatisfactorily in the Southwest Pacific areas, 
there was no time to await results from such a long- 
range program. Instead many commercial materials 
were tested as is, and this section includes a summary 
of the results obtained. 

In the usual case, the results reported Avere obtained 
on plastic samples that were neither sterilized nor 
cleaned in any special way. Up to 1946 there has been 
no demonstration of a method of sterilization of 
plastics that will prevent growth of contaminating or- 
ganisms on the piece without altering the material. 
Ultraviolet exposure for a short period of time has 
been recommended but not yet tried. The effects of 
A’olatile fungicides on plastics have not been studied, 
although such treatments with methanolic vapor and 
chloropicrin have been suggested. With volatile fun- 
gicides, one has the disadvantage of eliminating iden- 
tical control conditions unless the sample under test 
is similarly treated. Wet and dry heat sterilization is 
thought to be more deleterious in effect than the other 
agents mentioned. Ozone treatment brings up the 
possibility of chemical change. However, the fact that 
most of the above discussion on treatments for steril- 
ization of plastics covers opinions rather than facts 
based on experimental evidence is indicative of the 
work that remains to be done on this problem. 

On the basis of results reported by the Sperry Gyro- 
scope Co.,* the Bakelite Corporation,^ the Materials 
Laboratory of the New York Navy Y^ard,® the Signal 
Corps Laboratory at Fort Monmouth,^®’^^ and the 
British Ministry of Supply,^^ certain conclusions may 
be draAvn. With the laminated materials, although the 
phenol -formaldehyde, urea-formaldehyde, and mela- 
mine-formaldehyde resins are inert, paper and cloth 
render the materials easily susceptible to fungal 
groAvth at cut edges. Of course, if the resin surface is 
broken in any manner and the cloth exposed, fungus 
Avill groAV there also. It is AAuth this type of material 
that the use of suitable varnishes on cut edges has 
been suggested. Laminated materials that contain 


46 


SYNTHETIC RESINS, PLASTICS, AND PLASTICIZERS 


glass cloth, mat, or asbestos cloth are quite resistant 
to fungal attack provided no susceptible sizing mate- 
rial like starch is on the cloth. 

The resistance of molded pieces to fungal attack is 
much better than that of laminated materials. Where 
cut cotton rag has been incorporated, susceptibility is 
great. However, wood-flour-tilled phenolics are not 
too susceptible to fungal attack, although in time they 
support a slight surface growth. The quality of the 
molded piece is very important in this case. Since 
molded pieces have no rough or cut edges, their in- 
creased resistance might be expected. Phenolics filled 
with glass, mica, and asbestos are very resistant to 
fungal attack. Molded plastics containing melamine- 
formaldehyde resins have perhaps a slight advantage 
over phenolic molding materials. 

If resistant plasticizers, as well as no excessive 
amount of susceptible lubricants are used, thermoplas- 
tics are quite resistant. Thus, polystyrene, polymethyl- 
methacrylate, polyethylene, and Nylon plastics, in 
which little or no plasticizers are used, are resistant 
to fungus. On the other hand, cellulose actetate as 
well as mixed esters of cellulose, ethyl cellulose, and 
polyvinyl materials in which large amounts of varied 
plasticizers are used pose a different problem. With 
these materials fungal resistance will vary from poor 
to excellent, dependent on the nature of the compo- 
nents in the plastic other than the resin. If proper pre- 
caution is taken to include only resistant components 
wherever feasible, the behavior of these materials un- 
der tropical conditions should be more satisfactory. 

5 5 EFFECT OF FUNGAL GROWTH ON 
PROPERTIES OF PLASTICS 

Since some properties of plastics are markedly in- 
fluenced by moisture alone, it is in an attempt to ob- 
serve changes in properties under conditions of fungal 
growth that the relative roles of moisture and fungus 
become interwoven. Especially in electric equipment, 
the change in properties introduced by moisture and 
fungus is detrimental to the performance of the equip- 
ment. The simple fact that fungi grow on the plastic 
is proof that the relative humidity of the surrounding 
atmosphere is at least 70 to 80 per cent, and probably 
considerably higher. In addition, any type of mold 
growth, however slight in quantity, acts as an agent 
for the condensation and entrenchment of further 
moisture. Thus, there may be an effect of fungus in 
addition to the effect of moisture on the properties of 
the plastic. 


Aside from a very few cases where a cellulose filler 
has been attacked, or a very susceptible plasticizer 
has been removed with resulting brittleness, no data 
demonstrating permanent alteration of properties of 
plastics due to fungal growth have been made avail- 
able. Lack of suitable control, as well as lack of work 
along this line, are probably responsible. 

It has been the experience of many that it is not 
possible to keep an unsterilized plastic sample under 
high humidity without having fungal growth due to 
the contaminating organisms on the sample. The ques- 
tion of sterilization of the sample to avert such growth 
for control purposes has already been discussed. An- 
other approach has been the use of an inert atmosphere 
such as that of nitrogen gas. Although it has been 
found that nitrogen gas stunts the growth of fungi, 
as yet it has not been demonstrated that such an at- 
mosphere would completely inhibit growth of fungi. 
There is a great deal of experimental work now being 
done on the question of obtaining a good control. 

5.5 ADDITION OF FUNGICIDES 

TO PLASTICS 

Even though some plastic materials are fungus- 
resistant, they are not fungistatic. Thus, debris and 
external contaminants on the material can serve as a 
source of fungal growth. During World War II at- 
tempts were made to render susceptible plastics fungi- 
static by the use of fungicidal coatings. In an ap- 
proach to the problem from another angle, fungicides 
were incorporated directly into plastics during their 
manufacture in an attempt to insure some degree of 
fungal resistance of the material without any subse- 
quent treatment. 

In all discussions about fungicides for plastics, it 
must be remembered that in many cases there may be 
no need for fungistatic plastics. When it has been 
definitely established that plastics made from the most 
resistant components are still unsatisfactory for cer- 
tain uses under conditions prevailing in the tropics, 
it may be true that fungistatic plastics are necessary. 
However, even though the need is still debatable, pre- 
liminary experimental work on this problem has been 
under way to explore the possibilities of making fungi- 
static plastics so that they would be ready if needed. 

In order for a fungicide to be effective in plastics, 
it should conform with the following requirements: 

1. The compound should be compatible with the 
resin. 

2 . The compound should have low volatility so as 


ADDITION OF FUNGICIDES TO PLASTICS 


47 


not to be lost during the molding operation. 

3. It should be sufficiently insoluble to resist leach- 
ing by water. 

4. The presence of the fungicide should have no 
significant effect on the physical properties of the 
plastic. 

5. The fungicide should be chemically inert so that 
it is not altered by reaction with other components of 
the plastic mass with a corresponding loss in fungi- 
cidal activity. 

6. Incorporation of the compound should not neces- 
sitate a drastic change in manufacture. 

7. The compound should be effective for a sufficient 
length of time, preferably the service life of the mate- 
rial. 

8. The compound should he nontoxic to the worker 
handling the material, or at least be relatively non- 
hazardous. 

9. The final product should offer no health hazard, 
such as a skin irritant, on continued use by personnel. 

At present it seems almost impossible to fulfill some 
of these requirements. For example, in order for the 
surface of the plastic to be fungistatic, an effective 
concentration of fungicide must always be present 
there. Presumably this requirement implies a constant 
loss of fungicide, the rate of which is dependent on its 
volatility as well as external conditions. From this it 
is evident that a fungicide should be effective in low 
concentration if the fungistatic property of the plastic 
is to have any appreciable life period. Preliminary 
work indicated that it was impossible to predict 
whether a given fungicide would function effectively 
in a given plastic system, and therefore experimenta- 
tion in this field was necessarily of an empirical na- 
ture. In one investigation''^ phenolic plastics were pre- 
pared with fungicides incorporated directly in the 
material. All the materials prepared were sent to three 
different laboratories for test. In most cases the fungi- 
cide was used in concentrations of 0.25, 0.5, 0.75, 1.0, 
1.5, and 2.0 per cent. In addition to the testing of the 
treated plastics, control samples of untreated plastics 
were included. In the compounding of molding resins 
the dry fungicide was added to the premix. Where fil- 
lers were included, two methods of treating the filler 
were used. In one case the paper or cloth was impreg- 
nated by immersion in a solution of the fungicide, 
and in the other case the fungicide was incorporated 
into the resin used to coat the filler. 

On the basis of fungal resistance alone, the incor- 
poration of salicylanilide was found to yield the best 
protected plastics. The compound is safe to handle, is 


compatible with the resins, has a vapor pressure low 
enough to prevent excessive losses during processing, 
and has a marked effect on the inhibition of fungal 
growth. Copper naphthenate was too disagreeable to 
work with, as well as fairly incompatible with the res- 
ins. The organic mercurials were a health hazard, and 
the chlorinated phenols were too volatile. 

Subsequently, the same investigators determined the 
effects of the incorporation of salicylanilide on the 
physical properties of the plastics.^^ Tests were con- 
ducted on molded and laminated phenolic compounds 
having 2 per cent of salicylanilide incorporated during 
the process of manufacture. The laminated phenolics 
so prepared comprised two fabric-base grades and 
three paper-base grades, the untreated controls meet- 
ing the requirements of JAN-P-IS specification for 
grades EM-1 (FBG), EM-2 (FBE), E-5, E-4 
(PBE), and M-1 (PBM). The molded phenolics made 
were those of which the untreated standard counter- 
parts meet the requirements of JAN-P-IA specification 
for grades E-1 (CFG), M-3 (CFI-10), E-4 (MFE), 
and one grade of melamine-resin asbestos-cellulose 
compound. The materials were tested according to the 
JAN" specification tests, and from an examination of 
the test data it was concluded that the addition of 
salicylanilide in 2 per cent concentration had little or 
no effect on the physical properties of the molded or 
laminated materials studied. 

Experimental work on fungistatic plastics has also 
been carried out at the Boyce Thompson Institute.^ 
Here, too, disappointing results were obtained with 
phenolic cloth laminates. The cloth was impregnated 
with 2 per cent of the fungicide, and then made into 
laminates with a phenolic resin. The following fungi- 
cides were tried: dihydroxydichlorodiphenylmethane 
(Preventol GD), U. S. Eubber No. 3, Intracol, Hy- 
drocide lOX Special (quaternary ammonium com- 
pound), copper naphthenate, Shirlan extra (salicy- 
lanilide), Milban (zinc dimethyl dithiocarbamate) and 
Merck 242 (tetrabrom-o-cresol) . In no case were the 
treated plastics fungistatic. In connection with this 
study it was found that when starch-sized duck was used 
in the laminate, the plastic was more susceptible than 
when de-sized duck was used. Paper-base laminates 
were easier to protect than cloth-base plastics. When 
phenolic-glass laminates are susceptible to fungal 
growth, the sizing on the glass cloth is often responsible. 

The incorporation of fungicides in vinyl chloride- 
acetate copolymer was also studied. The fungicides 
were incorporated into the mix in 2 per cent concen- 
tration. Preventol, copper naphthenate, Hydrocide 


48 


SYNTHETIC RESINS, PLASTICS, AND PLASTICIZERS 


lOX Special, and Milban gave some protection to the 
material which was plasticized Avith tricresyl phos- 
phate and methyl acetyl ricinoleate. Milban seemed 
to be the best fungicide from the standpoint of soil- 
burial tests. After hanging for 100 days in a tropical 
room, the plastics treated with fungicides were less 
overgroAvn by fungi than the control sample. Thus, 
fungicides in polyvinyl materials do have some bene- 
ficial effect in 2 per cent concentration, and possibly 
higher concentrations would afford better protection. 

A considerable amount of experimental Avork has 
also been done on the incorporation of mercurial fun- 
gicides in thermoplastics.^^ Concentrated solutions of 
phenyl mercuric fungicides in plasticizers Avere used 
such that the final concentration of the fungicide in 
the plastic varied from 0.25 to 2.0 per cent. In this AA'ork 
the fungicides had to be carefully purified to be effec- 
tive, and Avdien such fungicides Avere used they Avere 
not easily removed by heating or leaching. The dif- 
ferent phenyl mercuric derivatives used Avere : phenyl 
mercuric acetate, phenyl mercuric phthalate, phenyl 
mercuric salicylate, phenyl mercuric stearate, and 
phenyl mercuric o-benzoic sulfimide. Plasticizers that 
are compatible Avith these fungicides are dibutyl tar- 
trate, dimethyl phthalate, Santicizer M-17, triacetin, 
triphenyl phosphate, and tricresyl phosphate. 

Using one or more of the above fungicides it Avas 
found that a number of plastics could be made fungi- 
static in that they passed the Signal Corps Specifica- 
tion 71-2202A using Aspergillus niger. Tests AAuth a 
spore mixture were also conducted. Among the cellu- 
lose plastics, cellulose acetate plasticized Avith Santi- 
cizer M-17, ethylcellulose plasticized Avith Santicizer 
M-17 or tricresyl phosphate, and cellulose nitrate plas- 
ticized Avdth tricresyl phosphate have been protected. 
Polystyrene as Avell as contact laminating resins of the 
styrene copolymer type have also been rendered fungi- 
static by the use of 0.5 to 1.0 per cent of a phenyl mer- 
curial fungicide such as phenyl mercuric phthalate or 
salicylate. Vinyl copolymers are also rendered fungi- 
static by the incorporation of less than 1 per cent of 
phenyl mercuric salicylate. 


Phenolic resins are much more difficult to protect, 
possibly due to the presence of formaldehyde Avhich re- 
acts Avith the mercurial fungicide at high temperatures. 
A phenol-formaldehyde, cellulose- filled plastic Avas 
made fungistatic by the addition of 2 per cent phenyl 
mercuric phthalate. In some cases 1 per cent fungicide 
Avas sufficient. HoAvever, from an overall picture it is 
the consensus of opinion that phenolic plastics, espe- 
cially laminates, are the most difficult to protect, and 
results are still inconsistent. Urea-formaldehyde mold- 
ing poAvders do not lend themselves readily to the in- 
corporation of fungicides. 

The problem as to health hazard has also been in- 
vestigated to some extent. There has been some criti- 
cism of mercurial fungicides because of their toxicity 
to human beings. In a report describing tests to de- 
termine the irritant and sensitization properties of 
fungicides in a polyvinyl plastic, it was found that 
the mercurials caused moderate to severe irritation.^^ 
HoAvever, proponents of these fungicides claim that 
toxicity is not a factor in the Ioav concentrations in 
Avhich these materials are used. 

NTo experimental Avork has been done on the problem 
as to Avhether the fungicide exists unaltered in the plas- 
tic after manufacture. Elementary analysis for such a 
constituent as mercury, nitrogen, or sulfur means little 
because this Avould not indicate Avhether further reac- 
tion of the compound Avith components of the plastic 
had occurred. The only indication that the fungicide 
does exist unaltered, at least in thermoplastic materials, 
is the increased fungal resistance of these materials. 

In summarizing, it can be said that a great deal of 
Av^ork remains to be done. As of today no treatment is 
knoAvn that Avill inhibit groAvth of fungi on all plastics, 
and if this is the desired goal, the problem is far from 
soh'ed. HoAveA^er, in a general way, thermoplastic mate- 
rials can be made more resistant to fungi by incorpo- 
rating fungicides in the plastic. The situation Avith 
phenolic materials is more obscure, and at present the 
incorporation of fungicides in susceptible laminates 
does not alter their fungal susceptibility to any ap- 
preciable extent. 


Chapter 6 

TROPICAL DETERIORATION OF PHOTOGRAPHIC 
EQUIPMENT AND SUPPLIES 


6 1 MAGNITUDE OF THE PROBLEM 

T o ILLUSTRATE the effects of tropical environments 
on photographic equipment and supplies the fol- 
lowing are quoted from information made available to 
the Tropical Deterioration Administrative Committee 
[TDAC].^ 

From Signal Corps Photographer, New Guinea, 
July 5, 1944. 

One item, perhaps trivial, is the breakdown and stripping of 
the leather covering on speed graphics . . . , once the moisture- 
proof paper (of film wrapper) is opened, it can’t be reused. 
This is a problem in some instances, because moisture and 
fungus sometimes attack the gelatin between the time of ex- 
posure and time of being transported to the lab for processing. . . 
Cut film is a tough problem because it isn’t tropically packed 
enough to prevent the formation of fungus . . . Blue and spider 
fungus nourished by moisture sometimes forms on the lenses 
and between the elements. 

From Signal Corps Photographer, India, July 24, 
1944. 

One of our boys has just returned from Burma, where he 
spent four months taking movies around Mytikyina, Mogaung, 
etc. He has presented me with a list of the difficulties encoun- 
tered up there. It seems that moisture is the chief demon as 
regards photographic materials up in that neck of the woods. 

. . . The leather on the back of the camera (where the 
holders are inserted) swells up with the result that no holders 
can be fitted in. The only remedy the boys find for this trouble 
is to remove all the leather from the back of the camera ... As 
for the flash equipment — it is practically undependable. The 
points corrode, batteries simply fall apart in the dampness . . . 

The cable release socket should be provided with a screw 
type plug otherwise moisture enters the shutter through the 
opening and raises havoc with it . . . One brand of 35 mm. 
cartridges swells so badly that they cannot be loaded in the 
Leica. For any photography in jungle country only the highest 
speed emulsions should be issued because there is not enough 
light for the use of Plus-X or Panatomic-X. 

Film gives a great deal of trouble and paper as well. The 
cut film swells and cannot be slid into the tracks of the holder 
— therefore, it must be trimmed on the cutter every time a 
photographer loads up. The film packs are worthless because 
when one goes to pull a tab out he pulls out five or six films 
which have stuck together inside the pack . . . 

In addition to the above quotations there were also 

“The quotations are taken from letter excerpts which were 
sent to TDAC by the Director of the Pictorial Engineering 
Research Laboratory, Signal Corps Photographic Center as 
evidence that real problems did exist with reference to these 
materials and in support of a request that the Subcommittee 
on Photographic Equipment and Supplies be organized. 


contained in these letter excerpts many comments on 
the unserviceability of particular makes of cameras. 
These are omitted so as not to refer to specific manu- 
factures, but included in them were unsatisfactory re- 
ports on fungus attack and short life of bellows, col- 
lection of moisture and rusting of metal shutters, pin- 
holing of focal plane shutters, corrosion of metal parts, 
and fungus attack of lenses. 

It is understandable that it is important and neces- 
sary to have photographic equipment and supplies 
which will be satisfactory under any climatic condi- 
tions. This has been stated^ in OSRD Report 6218.’^ 

Some insight as to the magnitude and potential 
economic significance of tropical deterioration as it 
concerns film alone is gained when it is realized that 
the estimated film consumption by the Armed Forces 
for 1945 (based on WPB Press Release 7080, January 
2, 1945, for the first quarter of 1945), was some 60 
million sq ft of X-ray film, almost 100 million sq ft 
of Aero film and some 500 million lin ft of 16-mm 
movie film. In the field it was not uncommon to 
process 35,000 prints of Aero negatives in a single day. 

6 2 NATURE OF THE PROBLEM 

The degradation of the major consumable supplies, 
film and paper, under tropical conditions is largely 
due to the fact that gelatin, the foundation of all sen- 
sitized materials, is a nutrient for fungi and is highly 
subject to the infiuences of moisture and high tempera- 
ture. An obvious solution to these problems was the 
use of some other material, which would be immune 
to attack by fungus and which would not be unduly 
affected by moisture and high temperatures. This, 
however, would have involved the development of a 
completely new art of sensitizing the new film and 
such a development would not have been compatible 
with the urgency of the problem and the necessity for 
quick solutions. 

The problems in deterioration of equipment (cam- 
eras) were of three general categories: (1) problems 

’’Unless otherwise indicated the remainder of this chapter 
is organized from and based upon information contained in 
this report. 


49 


50 


PHOTOGRAPHIC EQUIPMENT AND SUPPLIES 


(‘onceriiing tlie deterioration of lenses, (2) problems 
eoneerning the deterioration of exteriors of the equip- 
ment, and (3) problems concerning the interiors of 
the equipment, mechanical parts, etc. The problems 
of lens deterioration closely parallel those which per- 
tain to optical instrnments such as hinoculars and 
Avhich are discussed in Chapter 3. Prohlems pertain- 
ing to the deterioration of exteriors of equipment were 
among those which could he most readily prevented. 
The commonly used materials snch as wood, leather, 
felt, cork, and glues, all of which are highly suscepti- 
hle to fungus attack, conld either he replaced by a 
substitute material which was immune to fnngns at- 
tack or they conld be omitted from the finished item 
when feasible. Protection conld be accorded to equip- 
ment which was already finished and in use hy the 
application of a protective finish or coating to serve 
as a moisture barrier and to which fungicides could 
be added. The problems which concerned the interiors 
of equipment and which involved mechanical parts 
were less readily solved and their solution could hope 
to be achieved to only a limited extent. These problems 
were mostly those of corrosion and were the result of 
the inability to seal the susceptihle portions completely 
against the ingress of moisture. 

The instances of faulty packaging of photographic 
equipment and supplies were strongly emphasized dur- 
ing the early stages of World War II. Certainly with 
photographic materials and the manner in which they 
were affected by tropical conditions, packaging prob- 
lems were as severe as with any other category of sup- 
plies. If such materials were packaged poorly and were 
subjected to severe handling in addition to the mois- 
ture and heat of the tropics, it conld only be expected 
that a high percentage of them would arrive in a use- 
less condition. Protection conld only be given to certain 
materials, e.g., film, by proper packaging and it was 
not to be expected that preventive treatments of other 
materials would in any sense be a substitute for good 
packaging. Proper pa(*kaging would still l)e necessary, 
in spite of preventive treatments, to insure that equip- 
ment and supplies would arrive in the theater in a us- 
able condition. The principles of proper packaging 
were common knowledge and correction of packaging 
faults was largely a matter of implementation ; cer- 
tain packaging prohlems nevertheless demanded fur- 
ther consideration. 

63 ORGANIZATION OF THE PROGRAM 

The program on prevention of deterioration of pho- 
tographic materials was conducted hy the TDAC Sub- 


committee on Photographic Equipment and Supplies. 
Among the studies which were made by the subcom- 
mittee were those which were authorized by Project 
AN-14.2, ‘‘Deterioration of Photographic and X-ray 
Film due to Fungus, Insects, and Moisture.’’ The em- 
phasis was placed on reviewing information which was 
readily available, and when additional studies were 
undertaken they were performed either by the meni- 
hers of the subcommittee or by contractors who were 
conducting other studies for TDAC. The program was 
organized under two main headings, (1) problems re- 
lated to consumable supplies (film, etc.) and (2) 
problems related to nonconsumable supplies (cameras, 
etc.). Termination of lYorld War II prevented the 
complete solution of all prohlems ; the extent to which 
they were completed is given in the following suni- 


mary. 


6.4 

PROBLEMS RELATED TO 
CONSUMABLE SUPPLIES 

6.4.1 

Gelatin Filters 


Among the problems related to consumable su})plies 
were those which concerned gelatin filters. The follow- 
ing discussion concerning gelatin filters is taken 
directly from the sid)conimittee report^ referred to 
previously. 

High atmospheric moisture causes the filters to 
swell and to l)ecome tacky. In such condition they are 
very susceptihle to fingerprints and handling marks. 
They often stick to the paper envelope in which they 
are shipped or come out of the envelope with a replica 
of the paper surface embossed in the gelatin surface. 
Moist or swollen gelatin is an excellent nutrient for 
fungi and bacteria, and although an unmarred filter 
may he successfully put into use, it may be only a few 
days before the filter becomes cloudy or spotted with 
fungus growth. Such growth as well as surface mark- 
ings render the filter optically unfit for use. 

The investigations on this subject were confined to 
the development of : 

1. Moisture-proof and/or fungus-proof lacquer coat- 
ings for existing gelatin filters. 

2. Filters made with nongelatin substitute mate- 
rials which would not support fungus growth. 

It was learned that the manufacturers of filters had 
adopted the principle that a moisture-proof lacquer 
with or without fungicides should be satisfactory and 
that experiments were already under way in this study. 
It has not yet been determined that a fungicide is 


PROBLEMS RELATED TO CONSUMABLE SUPPLIES 


51 


necessary, iiiasiiiiicli as a moisture-proof, noiiiiiitrient 
lacquer may suffice. The time has been too short to 
make a full investigation of the possible effects of the 
lacquers on printing operations and particularly on 
the transmission curve of filters where color compen- 
sation may be involved in reproducing color prints. 
Preliminary reports from the field indicate that lac- 
quered filters represent a definite improvement as far 
as retarding the swelling of gelatin and the prevention 
of fungus growth are concerned. 

Filters cut from large lacquered sheets are vulner- 
able to attack and infection by fungi along the cut 
edges. If left in contact with water the lacquer coat 
tends to peel. Only meager information was obtained 
on the names of fungicides used in lacquering experi- 
ments, but in general they were compounds known to 
have good fungicidal properties. 

As a result of this activity it seems that the appli- 
cation of lacquer-dipped coatings offers an immediate 
alleviation of the problem and it is recommended that 
filter manufacturers be encouraged to continue the 
work. It is apparent that lacquering technique is 
needed to cover the edges of the filter. It is also recom- 
mended that consideration be given to a specification 
requiring that filters be packed in heat-sealed foil en- 
velopes to insure keeping until they are put into use. 

The substitution for gelatin of nonnutrient mate- 
rials such as cellulose acetate, Lucite, or some of the 
recently developed polymers could not be undertaken 
due to existing conditions, but such materials merit 
consideration in any long-term program that may be 
undertaken. 

^ 2 Containers for Chemicals 

Attention was also directed to problems concerning 
containers for chemicals. Reports and data from the 
field revealed the numerous shortcomings of standard 
cardboard or metal containers. These would not exclude 
moisture nor withstand rough handling. For chemicals 
which do not require a glass container a rip-strip sol- 
dered can with lithographed labels and an external 
application of corrosion-resistant lacquer had been 
found satisfactory in tropical areas. The chemicals can 
be packed loosely in the cans or in cartons which are 
placed in the cans. The corrosion-resistant lacquer pre- 
vents or retards corrosion and subsequent exposure of 
the contents to moisture. 

Paper labels have generally proved unsatisfactory 
for tropical use since they would become detached or 


would be destroyed partially or entirely by insect or 
fungus attack; this was a particular problem with 
glass containers. After considerations of alternative 
methods of labeling glass and the cost of each method, 
it was recommended that labels made with ceramic 
pigments (such as those used in the soft drink trade) 
would probably be most satisfactory; however, the use 
of tropical lacquers for this purpose should be investi- 
gated further, since the use of lacquers would possibly 
be less expensive and more convenient where a small 
number of any one type of label was involved. 

^ ^ Containers for Photographic 
Film and Paper 

Many types of problems were involved in the con- 
siderations of containers for photographic film and 
paper. These are presented in detail in OSRD Report 
6218.^ The requirements that packages of these mate- 
rials be waterproof and moisture-resistant and that 
they be able to withstand rough handling and pro- 
longed storage in the tropics are paramount. The phy- 
sical nature and form of the packages were shown to 
be important from the viewpoint of susceptibility to 
damage and convenience in storage. A very important 
feature which deserved attention was that some pro- 
A'ision be made for containers and wrapping materials 
which could be used in the field after the original 
package was opened and partly used. 

Reports were received that heat-sealed foil and 
x-crepe wrapping were satisfactory for keeping films 
dry during shipment and storage in tropical climates. 
With such packaging, film and paper could usually be 
kept beyond its expiration date. Other aspects of over- 
seas packaging were also satisfactory. It was learned 
that the Eastman Kodak Company had undertaken 
a broad experimental program on packaging to obtain 
further improvements for application to materials sent 
to the tropics. 

Information gained from this program was made 
available to the Subcommittee on Photographic Equip- 
ment and Supplies and is reported in OSRD Report 
6218.^ Packaging principles which were established for 
photographic equipment and supplies as the result of 
these investigations are given in the report as follows. 

1. The individual unit of sensitized product must 
receive satisfactory moisture-vapor and liquid-water 
protection by the use of a packaging material or com- 
bination of materials which will permit rough han- 
dling. 


52 


PHOTOGRAPHIC EQUIPMENT AND SUPPLIES 


2 . A satisfactory package is one which will with- 
stand three niunths’ keeping at 100 F and 90 to 95 
per cent EH without permitting a relative humidity 
change in the product greater than 10 per cent, that 
is, material originally in equilibrium with 50 per cent 
1\H shall be in equilibrium with a relative humidity 
not exceeding 60 per cent EH after such storage. 

3. Complete moisture-vapor protection can be at- 
tained only with the use of a solid sheet of metal 
which can he completely sealed. Other materials, seal- 
ed or unsealed, can otfer complete protection to liquid- 
water leakage and various degrees of moisture- vapor 
leakage but none otfer complete moisture-vapor pro- 
tection. 

4. Certain boxboard materials are preferably used in 
such a manner as not to be included inside the hermeti- 
cally sealed packages. Such usage prevents a possible 
moisture reservoir as well as possible contaminators 
from being in the position of potential troublemakers. 

There are also given in OSED Eeport 6218^ descri])- 
tions of the types of packaging which have been applied 
in accordance with the above principles to the follow- 
ing materials: sheet film, both portrait and X-ray; 
film packs; amateur black and white roll films; color 
roll films; amateur and professional motion picture 
film in rolls; amateur motion picture film in maga- 
zine; gun camera refills; aerial films; dental X-ray 
lilms; papers. 

The foregoing paragraphs indicate that the prob- 
lem of packing for overseas shipment was remedied 
to a large extent within the time that innovations 
could be ])ut to practical use. There still remained, 
however, the need of some means of protecting films 
and papers after the overseas packaging had been re- 
moved. Modification of packs in use to allow resealing 
did not appear to be possible. It was suggested that 
separate envelopes be included in a package for re- 
wrapping portions of the pack which were not used 
immediately. An alternate suggestioii was made that 
an auxiliary wrai)per, consisting of an envelope with 
an efficient type of fold, he used in conjuction with 
the overseas wrapper; this would then he in place after 
the overseas wrapper was broken. An obvious remedy 
to this problem would be to employ unit packaging of 
films and papers wherever possible, and with the 
proper materials, protection could be given to individ- 
ual items until they were used. It is conceivable that 
the expense which might be involved in this would be 
prohibitive, but the subcommittee recommended that 
work be continued on this aspect of the packaging of 
films and papers. 


Deterioration of Photograpliic Film 

In October 1943 the deterioration of developed pho- 
tographic film was briefly described in the Australian 
report of the New Guinea Science Mission which 
stated that mold grew on films after development and 
caused spotting in prints made from such films. Xo 
other field reports on this subject were brought to the 
attention of TDAC until December 1944 and January 
1945 when reports from members of the Panama 
Science Mission indicated that the problem was one 
of some concern to the Photographic Laboratory of 
A1 brook Field.® 

These observations along with others were also cited 
in OSED Eeport 5685.- Attention was further di- 
rected to the problem in ^larch 1945 by an Army 
request for investigation of possible protective meas- 
ures for processed film. The need for these was indi- 
cated by informal reports made to the Maintenance 
Division, Headquarters, Army Service Forces. As 
indicated previously, this project was assigned to 
the Subcommittee on Photographic Equipment and 
Supplies. 

From a military view the principal reasons for which 
it is desirable to prevent deterioration of developed 
film are that negatives constitute important historical 
records of units, campaigns, etc. For individual med- 
ical records X-ray files are of equal importance. Fre- 
quently, if a negative is damaged, but still usable, 
much time and trouble is expended before a suitable 
print is obtained from it. It may be impossible to 
obtain satisfactory enlargements from such negatives. 
Whenever it is necessary to store developed films in 
the tropics these problems are encountered unless 
facilities for control of both moisture (humidity) and 
temperature are availal)le. The problem is no doubt 
aggravated by the conventional and perhaps necessary 
practice of storage in envelopes with little or no 
chance for air circulation around the film. With long- 
time storage it is not difficult to visualize extreme 
fungus attack in Avhich the gelatin is badly etched. 
Without adequate storage conditions in the tropics, 
important photographic records could only be kept 
free from fungus attack by constant inspection and 
attention. This has been indicated by officers who have 
returned from Pacific areas. - 

An interesting feature of some developed films 
which are attacked by fungi is that they develop blue 

^Personal correspondence from E. S. Barghoorn, Jr., to Gus- 
taviis J. Esselen concerned the problem and cooperation with 
Air Force ])ersonnel in preliminary investigations. 


PROBLEMS RELATED TO CONSUMABLE SUPPLIES 


53 


spots in the area of the inyeeliiim. The blue spots are 
confined to the back of the film and, further, to those 
types on which a blue antihalation dye had been used. 
It was suggested by Barghoorn (personal correspon- 
dence) in Panama that the dye is sensitive to pH 
changes and under the influence of metabolic products 
of fungi the color reaction was produced. Alternate 
suggestions in explanation of the color reaction have 
been made.^’^ These indicate that after the developing 
bath, when the blue dye is reduced to a colorless form 
by the action of sulphite, the colorless form of the 
dye is not entirely removed by washing, and with 
presence of fungus growth it is reoxidized to the 
color state. However, Barghoorn indicated (corre- 
spondence) that if film is developed in pyro developer 
the spots do not appear. Also, it has been stated^ that 
the color can be produced by application of an acid. 
It is interesting in this connection that Barghoorn 
observed (correspondence) that a species of Penicil- 
lium was capable of extracting the pigment and con- 
centrating it in the blue form in spores and hyphae. 
Further investigation seems to be necessary in order to 
determine what, if any, relationship exists between 
the suggested pH reaction and the oxidation-reduc- 
tion reaction in producing this color spotting. This 
phase of the problem is not of primary importance, 
but these matters should be clarified in order to 
achieve a complete understanding of the situation. 

Among the treatments which have been used in the 
field to eliminate fungus spotting of developed film 
is the use of Merthiosal (0.1 per cent) dissolved in a 
mixture of acetone, ethyl alcohol, and propyl alcohol 
and applied to the film. In the reported trial this was 
applied to Kodachrome movie film;^ in addition the 
film reels and cases were painted with Merthiosaled 
paint. This treatment proved to be very effective in 
preventing fungus growth. OSRD Report 6218^ indi- 
cates that preliminary reports were brought to the 
attention of the Subcommittee on Photographic 
Equipment and Supplies that some manufacturers 
were conducting experiments to incorporate a fungi- 
cide in emulsion at the time of manufacture, but it 
was difficult to find a compound that would not affect 
the photographic properties of the emulsion and at 
the same time would not wash out during the process- 
ing. Another approach which had received some inves- 
tigation concerned the use of a fungicidal lacquer. 
In investigations arranged by the subcommittee on 
this problem, various fungicides were applied in aque- 
ous solution to the developed film. These are reported 
in OSRD Report e5685^ and reference is made to them 
in OSRD Report 6218.^ 


In the tests referred to in the preceding paragraph, 
the majority of the treated films were exposed in the 
tropical house, but some petri dish tests were made. 
The observations which were made included the pres- 
ence or absence of fungus growth and the degree to 
which softening of the emulsion occurred. Certain 
experimental treatments, even though they prevented 
the growth of fungi, caused a softening of the emul- 
sion. After prolonged exposure, certain treatments 
which were initially satisfactory permitted fungus 
growth, or caused a tacky or soft emulsion, or both. 
The consistency of performance was considered in 
evaluating the efficacy of the various treatments. The 
end of World War II prevented the completion of 
studies underway, but several promising leads were 
obtained. 

The most satisfactory compound in these experi- 
ments was a mixture of high molecular alkyl-dimethyl- 
benzyl-animonium chlorides which is marketed under 
the trade name of Roccal. The commercial solution 
contains 10 per cent of the active compounds and the 
dilutions indicated were made of the commercial 
preparation. In petri dish tests, which are far more 
rigorous than tropical house tests, a dilution of 1/100 
applied to film was sufficient to keep it free from 
fungus for a period of at least two weeks, the period 
of the test. At the end of that time the emulsion re- 
mained hard. In a tropical house test lasting two weeks 
all samples of a dilution series ranging from 0.1 to 
100 per cent remained free of fungus while uniform 
growth was present on both sides of untreated control 
samples. No undue softening of the emulsion occurred 
in any of the treated samples, except in the samples 
treated with the full strength solution which were 
slightly tacky. One report from a film manufacturer 
who performed functional tests on samples treated 
with a 1/10 dilution indicated that no undesirable 
effect was produced by the treatment. 

Among the other treatments which showed promise 
in these tests were the mercurial fungicides of Merthi- 
olate and Semesan. Mercury derivatives may be toxic 
to personnel and they are potential darkroom con- 
taminants. Since safer materials seem to be more 
promising, further investigation of the effectiveness 
of mercury compounds as fungicides to be applied 
to developed film was not recommended. In this con- 
nection, consideration was given to the overall effects 
of Merthiolate used as a fungicide on photographic 
materials. Extensive use has been made of this com- 
pound in the Pacific areas, chiefly in lacquers for 
fungus-proofing cameras. Experiments have shown 
that film can be fogged by Merthiolate, but tests in 


54 


PHOTOGRAPHIC EQUIPMENT AND SUPPLIES 


which Merthiolate-treated parts did not come in con- 
tact with film were negative. It is probable that a 
cautious use of Merthiolate-doped lacquers would be 
practical, if application were restricted to those parts 
such as lens barrel, cone, and external surfaces which 
do not come in contact with the film. 

One other promising suggestion has resulted from 
the exposures of experimentally treated film. Nylon 
dissolved in propanol did not prevent fungus growth, 
but it did prevent softening of the emulsion, thus in- 
dicating that it serves as a good moisture barrier. It 
is conceivable that superior performance would be 
obtained if a suitable fungicide such as Eoccal could 
be applied in a moisture-proof coating such as Nylon, 
and this possibility deserves further exploration. 

The possibility of overcoming the problems of fun- 
gus growth of developed film by improved storage 
envelopes is also considered in OSRD Report 6218.^ 
It was suggested that improvement can be made by 
the use of fungicidally treated paper or by the use of 
extruded tubes of thin plastic material which would 
be relatively resistant to fungus and be moisture- 
vapor proof. 

Also given in OSRD Report 6218^ are brief direc- 
tions for the cleaning and restoration of fungus-fouled 
negatives so as to enable them to be used with im- 
proved results. 

65 PROBLEMS RELATED TO 

NONCONSUMABLE SUPPLIES 

The classes of deterioration of equipment such as 
cameras were previously indicated (Section 6.2) as 
(1) deterioration of lenses, (2) deterioration of ex- 
teriors of equipment, and (3) deterioration of in- 
teriors of equipment, mechanical parts, etc. As with 
other materials, the deterioration is the result of the 
effect of moisture and fungus, or both, and therefore 
no new fundamentals are introduced. OSRD Report 
6218^ summarizes in detail the nature of all these 
effects and enumerates the most feasible methods for 
protection of cameras and other equipment. 

^ ^ ^ Protection of Lenses 

Fundamentally, the reasons for the deterioration 
of lenses in cameras are those which are given in Chap- 
ter 3 in the discussions concerning optical instru- 
ments. These problems in all sorts of equipment em- 
ploying optical systems are closely parallel, except 
possibly in remedial and preventive treatments, where 
limitations will be imposed by the nature of the 
equipment, its design, and use. It would be expected. 


therefore, that fungus and moisture Avould affect all 
lenses similarly, and experience has shown this to be 
the case. The fungicides Merthiolate (Merthiosal), 
Cresatin, and fenchyl thiocyanoacetate have been 
used to prevent fungus development in the optical 
parts of cameras. Of these, Merthiolate and fenchyl 
thiocyanoacetate have possibly been more widely used. 
Both of these would seem to be more easily applied 
than Cresatin capsules which have been used for binoc- 
ulars, primarily because of the space problems between 
lenses where the need for treatment is the greatest. 
Merthiolate can be applied in a 0.2 per cent solution 
in a flat black optical lacquer to lens flanges and the 
inside of lens barrels in an attempt to cover all proxi- 
mate parts without getting the mixture on the lenses 
themselves. Fenchyl thiocyanoacetate can be applied 
in the Carbowax mixture, given in Chapter 3, to 
screw threads as well as in a lacquer to other internal 
surfaces. 

2 Deterioration of Camera Exteriors 

The nature of the deterioration of exteriors of 
cameras and other equipment by moisture and fungus 
depends on the nature of the construction and the 
finish. To mention a few such effects — wooden portions 
may have joints loosened and support fungus growth; 
leather will mold and peel off wooden or metal cases; 
aluminum and other metals will corrode; and, bel- 
lows will deteriorate and develop pinholes. Carrying 
cases will also he affected by moisture and fungus 
since fabrics, felt, cork, etc., used in such carrying 
cases, are susceptible to deterioration and in addition 
to the deterioration of the cases themselves, more 
severe conditions result for equipment stored in such 
cases. In many cases performance of equipment has 
been improved by stripping unessential finishing items 
from the equipment or by substituting for them less 
susceptible materials. Improved performance also re- 
sulted from ap])lications of fungicidal laccpiers and 
varnishes to such materials which could he protected 
in this manner. In addition to such procedures, im- 
])roved maintenance and storage conditions could vast- 
ly lengthen the service life of equipment. Maintenance 
and storage procedures will be discussed in a later 
section. 

6.5.3 Deterioration of Camera Interiors 

Because of the fact that cameras and other photo- 
graphic equipment are of unsealed construction, de- 
terioration of internal parts and components is little 
different from deterioration of exteriors except for the 


PROBLEMS RELATED TO NONCONSUMABLE SUPPLIES 


55 


fact that iiiecliaiiical and functional parts are involved. 
Except for a certain few parts, one point in contrast 
between external and internal metal parts, particularly 
in aircraft cameras, is that external parts usually 
have a baked protective finish, whereas such a finish 
or plating is not compatible with the functional oper- 
ation of the inner parts. Therefore, rust preventives 
and lubricants must be relied on to maintain the 
working parts in good condition. 

No attempt is made here to cite the numerous diffi- 
culties which result from corrosion of the various 
parts of aircraft and ground cameras. OSRD Report 
6218^ thoroughly analyzes the effects of corrosion of 
susceptible parts. In aircraft cameras corrosion can 
affect the camera drive, film magazine, and many 
parts of the complex shutter mechanism. In ground 
cameras shutter mechanisms can be similarly affected, 
as well as the focusing mechanism, whether it is of 
the helical screw type or the rack-and-pinion type. 
In any camera, of course, lens screw threads may cor- 
rode so that it is impossible to remove the lens for 
replacement or cleaning. The only safe method of 
combatting these potential difficulties is by frequent 
inspection and maintenance (lubrication and the use 
of rust preventives) ; this is called for despite the 
adequacy of storage facilities. Lacquers can be used 
to advantage on metal parts which are not working 
surfaces. 

Storage Conditions 

The basic preventive which can be applied to pro- 
tection of photographic equipment is dry storage con- 
ditions. Photo equipment undergoes little if any de- 
terioration while in use. Under certain operating 
conditions, of course, such storage facilities are out 
of the question, but in more or less established bases 
they are possible. Essentially they are nothing more 
than a hot room or dry locker; the size can be varied 
with the need, but they should be no larger than 
necessary to store the equipment. In general, the room 
should be as airtight as possible with an adjustable 
vent and a heat source such as electric lamps or a 
heater with blower attachment. The floor should be 
elevated from the ground to provide for circulation 
below. Care must be taken that air circulates in and 
around the equipment and no air traps occur. Such 
storage facilities coupled with an active inspection 
and maintenance program should eliminate many 
difficulties in camera deterioration. 


^ Iiiiprovements in Design 

Eundamental progress can be achieved in reducing 
deterioration of equipment under tropical conditions 
by improvement of design and construction. The fol- 
lowing recommendations for future design have been 
included in OSRD Report 6218.^ 

It has been stated that little of the photographic 
equipment used by the Armed Forces was designed for 
the abuse and for the extremes of climate and handling 
which it had to withstand. This fact is absolutely true 
and it is the reason why so much trouble was experi- 
enced with ground photographic equipment in the 
tropics. Hand cameras and accessory equipment used by 
the Army and Navy photographic personnel remained 
the lightly built, difficult to repair, commercial in- 
struments that will not stand up under war conditions. 

Camera equipment for war should be designed to 
permit quick disassembly. The mechanism should be 
easily accessible, through inspection plates, making it 
unnecessary to tear down a unit to lubricate or in- 
spect it. All major components should be interchange- 
able for easy replacement in the field. It should be 
possible, for instance, to remove a focal-plane shutter, 
as a complete unit, and slip another one in place in a 
couple of minutes. Between-the-lens shutters should 
be sturdy and interchangeable. 

The entire camera should be constructed of metal 
with a noncorrosive finish and of weather-resistant 
properties. Range finders and flash sockets should be 
built in and protected from rain or spray. Making these 
accessories integral with the camera also eliminates the 
possibility of their loss, which would immediately 
render camera operation incomplete. Leather or fabric 
should be eliminated from the military camera. 

Controls should be oversize and sturdy. Wind and 
trip action, especially in cameras having both between- 
the-lens and focal-plane shutters, should be made fool- 
proof by interlocking mechanisms. 

Most important of all, cameras particularly, and 
other photographic equipment to a lesser extent, 
should be designed to come apart in a matter of 
minutes to permit quick repairs. Rifle construction 
is not impossible in a combat camera and it is 
highly recommended that this be kept in mind in 
future designs. An infantry man automatically takes 
his gun apart for cleaning at frequent intervals. There 
is no reason why the combat photographer’s camera 
cannot be built with the same idea in mind. The de- 
sign should be such that it would be impossible to 
reassemble the camera incorrectly. This can be done by 


56 


PHOTOGRAPHIC EQUIPMENT AND SUPPLIES 


keying the components so they will fit only one way. 

It would be a great help to the camera manufacturer 
as well as to the Army and Navy experimental labo- 
ratories if all captured enemy photographic equip- 
ment were submitted to them for engineering study 
as quickly as possible. Many excellent features have 
been found in the German and Japanese camera 
models of World War II that could have been used to 
advantage by American designers. 

Regardless of the improvement that can be made in 
design, it will probably always be necessary to store 
the equipment for periods and to arrange for main- 


tenance of a sort. As a result of new design and im- 
proved materials a superior degree of resistance can 
be imparted to a camera or other item of equipment, 
but even with this there would be a limit beyond which 
undesirable effects would result. With fewer and 
simpler maintenance procedures and problems it 
should be relatively easy to instruct personnel in the 
details and their importance. Innovation of design, 
together with the use of ideal storage conditions and 
adherence to a rigid maintenance program will con- 
siderably reduce or even eliminate tropical deteriora- 
tion of photographic equipment. 


Chapter 7 

TROPICAL DETERIORATION OF ELECTRIC AND 
ELECTRONIC EQUIPMENT 


7 1 STATEMENT OF THE PROBLEM 

M ost of the repoets which discuss the tropical 
deterioration of electric and electronic equipment 
have indicated that moisture is a prime agent of de- 
terioration. High and fluctuating temperatures and 
humidities result in the ingress of water vapor with 
subsequent condensation and deleterious effects in me- 
chanical and electrical properties of materials. Absorp- 
tion of moisture lowers resistance, films of water cause 
surface leakage, and absorption within a condenser or 
a coil can bring about serious alterations in the elec- 
trical constants of a circuit. 

Fungi are also important agents of deterioration in 
electric and electronic equipment. Hyphal strands of 
surface-growing fungi can introduce leakage paths 
which reduce insulation resistance and establish 
couples which promote electrolytic corrosion. A coat- 
ing of mold encourages the formation of a water film 
over surfaces and furnishes loci for droplet condensa- 
tion. Moldy surfaces dry slowly because air diffusion 
is retarded. Moisture retention by surface mold en- 
courages corrosion of metal parts as do organic acids 
which are produced in the metabolic activity of the 
fungi. Further, prolonged exposure to actively grow- 
ing fungi results in chemical breakdown of finishes 
and coverings. 

Reports of the Naval Research Laboratory^ and the 
British Ministry of Supply^ are representative of those 
which discuss these factors. The subject has also been 
brought before the general public by means of articles 
which have appeared in technical journals.®*^ With 
the book. This is Serious — Tropicalization/ the Sig- 
nal Corps directed the attention of manufacturers of 
Signal Corps equipment to the problems in order that 
the level of performance of equipment in the tropics 
would be improved. 

7 2 REMEDIES APPLIED 

It is probable that no item of electric and electronic 
equipment was immune to the effects of tropical con- 
ditions. To be sure, many items were designed for 
continuous use and as a general rule little difficulty 


was encountered with such equipment while in actual 
operation, since the increased temperature and the 
resulting lower relative humidity did not permit 
moisture effects nor the growth of microorganisms. 
However, these factors did not guarantee immunity 
from tropical effects during periods of transit and 
storage. Improved methods of packaging were there- 
fore necessary for electric and electronic equipment 
as well as all other types. This was but one phase of 
the problem; the more direct methods of approach 
involved the development of a higher resistance to 
tropical conditions in the equipment itself. 

Among these latter methods of approach which were 
advocated in the reports cited above were the follow- 
ing : Substitution and addition of parts and/or mate- 
rials, redesign of equipment, and such remedial meas- 
ures as improved storage conditions, hermetic sealing 
when possible, the use of dessicants or other means of 
drying, the use of volatile fungicides, and the applica- 
tion of protective varnishes or lacquers to serve as a 
barrier against moisture. These remedies were brought 
to the attention of personnel in the field by means of 
technical bulletins of the Army and Navy,^’’'^ in order 
to clarify the problems and to serve as a guide in 
maintenance and repair work. 

Of all of these remedial measures, the use of pro- 
tective varnishes and lacquers was perhaps the most 
significant and was given the greatest emphasis. This 
method of approach provided a ready means whereby 
equipment which was then in the field could be tropic- 
proofed and thereby have its service life extended. This 
method consisted of applying the protective lacquer 
or varnish by spraying, dipping, or brushing to the 
surfaces of finished assemblies or components after 
masking of parts over which such a coating would be 
undesirable, such as electric controls, relays, bearings, 
open switches, etc. As a protection against fungi, 
suitable toxic agents (fungicides) were added to the 
coating material. Such treatments were required in 
all Signal Corps equipment, and they were used exten- 
sively by other branches of the Armed Forces as well. 

The use of protective coatings was recognized as 
only a temporary expedient ; in practice, retreatments 
were usually necessary after periods of about six 


57 


58 


ELECTRIC AND ELECTRONIC EQUIPMENT 


months. More lasting improvement was possible by 
change of design and the use of materials which were 
less susceptible to the effects of moisture and fungus. 
Detailed considerations were given concerning the 
choice of resistant materials in some of the reports 
cited above^’-’^’ and others. Likely directions for im- 
proved design were also given.®’® 

7 3 need for fundamental 

INFORMATION 

As information accumulated from field reports and 
from the investigations conducted by xArmy and Navy 
laboratories, it was apparent that certain fundamental 
studies would be necessary before the protection of 
electric and electronic equipment could be improved 
beyond that given by practices which were then stand- 
ard. Many questions and problems had arisen which 
could only be answered by these studies. 

Much of the evidence from the field indicated that 
many failures in performance were due primarily to 
moisture effects as a result of high humidities and 
this tended to obscure the precise role which fungus 
held in the deterioration of such equipment under 
service conditions. On this basis some investigators 
felt that the incorporation of a fungicide in any pro- 
tective lacquer or varnish was unnecessary. Further- 
more, the question of the necessary and effective con- 
centration of an included fungicide in a protective 
coating and the advantage of one or another of the 
various fungicides available for this use were much 
discussed, not only with reference to their fungicidal 
effectiveness, but with reference to toxicity effects on 
personnel as well. It was argued that for certain ap- 
plications, lacquer possessed advantages over var- 
nishes because of their shorter drying time, but prac- 
tically all reports which discuss this point indicate 
that liigh -grade varnishes (phenolic resin tung oil 
type) have a higher water resistance. 

7 4 FUNGUS GROWTH ON HOOKUP WIRE 

In requesting Project AN-14.1, ^Tungus Growth on 
Hookup Wire,^’ the Signal Corps Standards Agency 
desired to obtain evidence which would settle these 
points of conflict. Not only was it desired to determine 
whether fungus will grow on hookup wire but also to 
ascertain whether or not there is a deleterious effect. 
If either braided or unbraided types of wire supported 
the growth of fungus it was requested that the per- 
centage and types of fungicides required to prevent 


the fungus growth be determined. It was also re- 
quested that investigations be made to determine 
the effect on the electrical properties of the wire of 
the leaching of the fungicides incorporated in the 
lacquers applied to the wire braid or insulation. 

A contract for these studies was arranged with the 
Rensselaer Polytechnic Institute. The immediate ob- 
jectives of the program as given in OSRD Report 
5692^® were as follows. 

1. The first phase was confined to a study of the 
role of fungus and moisture in the deterioration of 
wire without respect to the role of fungicides in affect- 
ing electrical properties. 

2. End tests were also to be made to determine the 
effect of moisture and fungus on the wear resistance 
of the various braided coverings used on the experi- 
mental wires. 

This investigation was begun in the summer of 1945 
and by the end of World War II only certain aspects 
were completed. Preliminary investigations deter- 
mined the methods of electrical measurements to be 
used as well as the methods of fungus inoculation. 
The conditions under which the tests were to be 
conducted and the methods of determining the wear 
resistance of test wires were also developed. 

^ Experimental Results and 

General Conclusions 

Preliminary experiments to determine suitable 
lengths of test wires and desirable spacing of elec- 
trodes yielded information on the creepage resistance 
of different wires under continued exposure at 100 
per cent relative humidity and in the presence of 
fungus growth. After exposure for twelve days the 
test wires were exposed to the room and allowed to 
dry for three hours after which the resistance was 
again measured. The wires used were the following 
types: SRIR with no braid, a type with polyvinyl 
chloride primary insulation having cotton braid and 
acetoproprionate lacquer finish, and a type with poly- 
vinyl chloride primary insulation with an extruded 
Nylon jacket. 

The results of this experiment are given in Figure 
1. It can be seen that the behavior of each type of 
wire follows the same general pattern. A sharp drop 
in resistance occurred over the first 24 hours after 
which the values remained relatively constant. When 
allowed to dry for three hours, after twelve days’ ex- 
posure in the test chambers, recovery was rapid. To 
accurately follow the course of recovery necessitates 


FUNGUS GROWTH ON HOOKUP WIRE 


59 


measurements immediately and at frequent intervals 
during the drying period. 

In addition to the results indicating the general 
behavior of the test wires, interesting observations on 
the test equipment and test methods were made as 
follows. 


drawn since only two samples of each wire type were 
used. 

2. However, there were indications that wires hav- 
ing the electrodes 2 in. from the ends showed a more 
rapid reduction in resistance which indicated that the 
resistance path over the ends was significant, and 



DAYS EXPOSURE AT 100 PER CENT RELATIVE HUMIDITY 


Figure 1. Creepage resistance between wrapped electrodes spaced 2 in. apart on 6-in. length of wire. 


1. In the attempt to determine whether a 2-, 3-, or 
4-in. distance between electrodes was most desirable, 
it was found that, since the variation in the resistance 
between apparently identical samples differed by as 
much as 100 per cent, no valid conclusions could be 


therefore the test method should be refined to elimi- 
nate this loss. 

3. The SRIE wires particularly showed heavy mold 
growth except for the region about 1 cm on each side 
of the copper electrode. Evidence was obtained which 



60 


ELECTRIC AND ELECTRONIC EQUIPMENT 


indicated that this was due to the fungicidal action 
of the copper rather than the electric current. Be- 
cause of this evidence it was decided to use platinum 
rather than copper electrodes. 

4. It was observed that the resistance in some sam- 
ples would increase by a factor of 5 or 10 if the test 
voltage were applied for more than a few seconds. 
Further investigation over ajydde range of test volt- 
ages will be necessary. 

7.4.2 Direction of Future Work 

To solve the problem fully, the role of each element 
of a complete insulated wire should be studied in re- 
lation to deterioration under humidity and fungus. 
The necessary wires for this have been assembled. 
It is expected that it will be possible to differentiate 
between the primary insulation, the braid or jacketing, 
the lacquer or varnish, and the fungicide. The elec- 
trical tests should proVide this information and the 
abrasion tests should relate the electric properties to 
the wear resistance of various wire components. Once 
the fundamental properties are known from the wires 
used, it will be possible to investigate the role of fun- 
gicides in the lacquers and varnishes. It has been 
suggested that certain fungicides are incompatible 
with the coating materials, that they deteriorate the 
electric properties of the wires, and that they are rap- 
idly lost during storage. When sufficient information 
is obtained to permit conclusions with respect to these 
questions, it will be desirable to check the results 
against chemical analyses. 

Despite the fact that it was only possible to begin 
these studies by the Tropical Deterioration Adminis- 
trative Committee, the important problems presented 
are being investigated further under the sponsorship 
of the Air Technical Service Command. 

7 5 EFFECTS OF MOISTURE AND FUNGUS 
ON ELECTRICAL INSULATING 
MATERIALS 

Investigations on this subject were closely related 
to those concerning hookup wire. The primary purpose 
in these studies was to sample a wide selection of 
laminated and molded thermosetting plastics and 
rigid thermoplastics in order to obtain information 
which would indicate the nature of their performance 
in equipment under tropical conditions. The program 
which was to be followed called for mechanical as 


well as electrical tests which were to follow Joint 
Army-Navy Specifications P-13, P-14, and P-15 as 
closely as possible. Inasmuch as exploratory work was 
necessary in the portion of the program involving 
the electrical determinations, this portion was under- 
taken first. As with the investigations on hookup 
wire, these too were begun in the summer of 1945 
and at the end of World War II only a satisfactory 
test method and a few preliminary results had been 
obtained. However, the majority of materials had been 
obtained, and by the end of September 1945 most of 
those on hand had been placed under. test. The lack 
of results from all samples under test is explained 
by the fact that inordinately long exposures and test 
periods are required to obtain significant information. 

A survey of Army, Navy, and industrial laboratories 
indicated that extensive systematic studies of the in- 
fluence of electrical and mechanical properties of plas- 
tics had not been niade.^^ Most of the work which had 
been done seemed to have been undertaken to solve 
specific and immediate problems involving selected 
plastics and the efficacy of fungicides and protective 
coatings in preventing fungus growth. Selected avail- 
able data are presented in the report cited above, and 
these should be more significant when evaluated in 
the light of information from these completed studies. 
The program is being continued by the Air Technical 
Service Command. 

From the data which were received, the deleterious 
effect of moisture on electrical insulating materials 
was apparent. Very few of the citations, however, relate 
fungus effects to moisture effects. Considerable em- 
phasis and importance was attached to the studies of 
H. L. Curtis, ‘Tnsulating Properties of Solid Dielec- 
trics,^^ (Bulletin of the Bureau of Standards, 1915, 
Vol. II, pp. 359-420), not only in these studies, but 
in others performed in Australia with particular ref- 
erence to insulating varnishes.^- Foremost among the 
conclusions of Curtis’ work is that surface conduction 
is the most important factor in determining the leak- 
age between two conductors insulated by a solid dielec- 
tric when in an atmosphere of high humidity. How- 
ever, there is a definite relationship between surface 
resistivity and the electrical characteristics of the 
dielectric as indicated by volume resistivity. 

7.5.1 Determining Methods of Test 

Preliminary investigations indicated that 2-in. 
diameter disks were suitable for surface-resistance 


EFFECTS OF MOISTURE AND FUNGUS ON ELECTRICAL INSULATING MATERIAL 


61 


measurements, and by employing a third electrode, 
volume-resistance measurements could be made on the 
same sample. In this three-electrode sample, the disk 
is mounted in a sealed glass jar with a metal top and 
all three connections are brought through by steatite 
bushings. The metal jar top becomes a part of a guard 
circuit and prevents leakage current (except on the 
sample) from getting into the measuring circuits. 
The electrodes on the samples consist of silver paint. 
Electrode III, iy 2 -in. diameter, is made in the center 
of one side of the 2-in. disk and on the opposite side, 
Electrode I, V 2 -in. diameter, is placed in the center 
while Electrode 11 covers the peripheral y 2 -in. of the 
sample. By suitable connections from a megohm 
bridge, electrostatic lines of force can be directed into 
the surface or into the volume. Humidity is controlled 
by saturated salt solutions in the bottom of the jar, 
and fungus is eliminated from control samples by the 
use of a nitrogen atmosphere. OSED Report 5691^^ 
describes this test method as well as the initial results 
on test samples. 

The specifications to be followed require a different 
method of measuring the electric properties but the 
investigations have indicated that the three-electrode 
sample provides more fundamental information due 
to the fact that surface and volume effects are separ- 
ately measured. However, the data from the three- 
electrode samples is being compared with data from 
the Pratt-Whitney Pin sample, called for in the speci- 
fications, with a view to effecting a correlation. 

In all samples which were inoculated for fungus 
tests, spores of Penicillium luteum have been applied 
by spraying. 


^ ^ ^ Experimental Results 

Early results are reported for selected laminated 
thermosetting materials and the rigid thermoplastic 
materials polystyrene, cellulose acetate, and acetate 
butyrate. The latter materials were exposed only to 
humidity, and after ten days polystyrene was virtually 
unaffected by humidity, acetate butyrate only slightly 
affected, while cellulose acetate showed a marked de- 
crease in both surface and volume resistances. 

Tests on the laminated thermosetting materials 
extended over 35 days. All show a great decrease in 
resistance and particularly a sharp drop in the initial 
24 hours. Comparison of data from the three-electrode 
samples with that from the Pratt-Whitney Pin sam- 
ples indicates that this decrease is primarily due to a 
drop in surface resistance. Although tests had not been 
in effect long enough to evaluate effect of fungus on a 
wide variety of materials, it is evident that where copi- 
ous fungus growth is present, the sample is found to be 
highly moisture absorptive. With fungus-attacked lam- 
inates the growth invariably started upon the cut edges. 

It is expected that with the separate evaluation of 
the effects of moisture and fungus upon the surface 
resistance and volume resistance of various types of 
plastics, the information will permit a realistic inter- 
pretation of the performance of electrical insulation 
under tropical conditions. The results from test sam- 
ples can be applied to such finished parts as octal 
sockets, tube bases, and J ones strips, but it is perhaps 
more important that they can furnish a working basis 
for the selection of high quality materials in the de- 
sign of new equipment for tropical service. 


Chapter 8 

COORDINATION OF TEST METHODS 


8 1 APPLICATION OF TEST METHODS TO 
STUDIES ON THE PREVENTION OF 
TROPICAL DETERIORATION 

T est methods are necessary and desirable during 
all phases of study on the prevention of tropical 
deterioration. The characteristics and properties of 
fungi and bacteria, the biological agents of deteriora- 
tion, are determined by various methods designed to 
indicate the ability of these organisms to thrive upon 
and thus deteriorate specific materials. In the develop- 
ment of protective treatments for materials, screening 
tests are employed to determine the merits of protec- 
tive agents which are promising. Tests for final evalu- 
ation of treated materials are considerably more re- 
fined than screening tests and include not only bio- 
logical tests but physical tests, such as exposure to 
moisture, heat, and sunlight, and others of an elec- 
trical or mechanical nature as may be required. In 
addition, a period of exposure in a tropical area has 
been used as a final test. 

Such tests which are generally referred to above 
may be descril)ed as research and development tests 
in that they constitute an integral part of any devel- 
opment program. In contrast to these are those tests 
which have been applied in the procurement of mate- 
rials, or ‘^specification tests.’^ ddiese are used to deter- 
mine the fitness of materials for tropical service by 
tbeir ability to meet standards which are regarded 
as adequate for indicating satisfactory performance 
in the tropics. 

Research and development tests which have been 
found to be useful in the development of methods of 
protection for optical instruments are given in the 
bibliographic entries of Chapter 3. Electrical test 
methods are discussed in Chapter 7 and given in 
greater detail in the references cited. The field ex- 
posure tests which have yielded valuable information 
on the prevention of textile deterioration are reviewed 
in Chapter 4. There are summarized in Chapter 0 
the results of the testing program in which the per- 
formance of a wide range of materials was deter- 
mined by exposing them to natural and simulated 
tropical environments. 

When the work of the Tropical Deterioration Ad- 
ministrative Committee [TDAC] was first started, 
there was no uniformity or general agreement as to 


test methods with the result that it was often im- 
possible to duplicate test results in different labora- 
tories. It was, therefore, obviously a prime essential 
to develop standard conditions for tests which could 
be agreed upon by all laboratories and thus permit 
duplication of results on a given sample regardless 
of the laboratory in which it was tested. It was for 
this purpose that the Subcommittee on Coordination 
of Test Methods was established. 

This subcommittee prepared GSR I) Report 6056,^ 
which summarizes and evaluates the test methods 
which have found wide application in tropical dete- 
rioration studies. The introduction to this report con- 
siders the primary factors which must be borne in 
mind in relating any laboratory test method to the 
particular use or service to be made of the items 
tested. The criteria upon which a choice of test or- 
ganisms should be based are also discussed. The dis- 
cussion on the early development of test methods in- 
dicates the various types of methods which have been 
employed, particularly in textile testing, such as pure- 
culture tests using different organisms, mixed-culture 
tests, soil-burial tests, and soil-suspension tests. With 
such tests as these, evaluation of the performance of 
tested fabrics is usually made by determining the re- 
tention of breaking strength. Initially, such test meth- 
ods were developed for evaluating protective treat- 
ments for textiles, but in a later section, this report 
indicates the use of natural and simulated tropical 
conditions, particularly in cases where these more or 
less refined procedures for textile testing are not ap- 
plicable. OSRD Report 6056^ also gives attention to 
the role of microorganisms in deterioration, methods 
for testing fungicides, physical conditioning of test 
samples, the testing of all types of specific Army and 
Navy materials, as well as a detailed review of various 
laboratory culture methods, soil-burial methods, and 
soil-suspension methods. 

8.2 TEST-METHOD STUDIES 

As stated above, the program on the coordination 
of test methods was undertaken in order to achieve 
uniformity in the testing procedures which were used 
by different laboratories and organizations. For many 
items or classes of materials, different test methods 
were in use, or different strains or species of fungi 


62 


TEST-METHOD STUDIES 


63 


were used by different groups in applying the same 
method. Not only was attention given to the coordina- 
tion of methods which were widely used, but studies 
essential to the development of certain new test meth- 
ods were also made. 

^ Hookup Wires 

The laboratory investigations in which the variable 
factors in the testing of hookup wires were studied are 
summarized in OSED Eeport 5686^ issued by TDAC. 
In the introduction to this report, the need for pro- 
tection against fungus growth on hookup wires is 
briefly stated. Because many different methods were 
being employed by the various laboratories concerned 
with the problem of fungus resistance of hookup wires, 
the Subcommittee on the Coordination of Test Meth- 
ods was requested to study this problem and to recom- 
mend a satisfactory method for an acceptance test for 
hookup wires. 

In order to determine the amount of variation in 
test methods used at different laboratories, a question- 
naire was sent to a number of laboratories which made 
routine tests on hookup wires. A resume of the replies 
to this questionnaire indicates variations in test meth- 
ods as follows. (1) All the laboratories questioned 
used a culture medium containing a nutrient, al- 
though all of them used an additional test consisting 
of soil contact, soil suspension, or a nonnutrient medi- 
um. (2) The temperature used varied from 25 to 
37 C. (3) The durations of the tests varied between 
five and thirty days. (4) There was considerable vari- 
ation in the organisms used in the test. Although most 
of the laboratories used Chaetomium, Aspergillus, 
and Penicillium, some had added Trichoderma and 
Actinomycetes, while a number used an unknown mix- 
ture. (5) All laboratories depended upon a visual test 
in expressing results. Several also used tensile 
strength, abrasion resistance, and electrical tests. This 
lack of uniformity of testing procedure could certainly 
be responsible for the expression of entirely different 
end results. It appeared evident that some standard- 
ization of a testing technique was desirable. 

In OSED Eeport 5686" the detailed results are given 
for exploratory tests on hookup wires using mineral 
salts agar, nutrient agar, soil contact, soil burial, a 
moist chamber, and pre-inoculation of filter paper 
moistened with a liquid culture medium in which 
fungus spores were suspended. These initial tests 
indicated that the method in which a mineral salts 
agar was used would produce more meaningful results 


in a shorter time and with less difficulty than with any 
of the other methods. Following these studies, experi- 
ments were conducted to determine the most suitable 
method for culturing fungi to obtain spores for inocu- 
lation of test specimens, and methods for inoculation. 
The test method as finally recommended is given in 
the Appendix of OSED Eeport 5686.- In this final 
method, advantage was taken of suggestions and com- 
ments from various Army and Navy laboratories to 
which a tentative method has been submitted pre- 
viously. This method was selected because it gave the 
most reliable and satisfactory results in estimating 
the fungus resistance of a wire under warm and humid 
conditions favorable to fungus development. The re- 
sults obtained by this method checked well with prac- 
tical observations in tropical chambers as well as 
under natural tropical conditions. 

Significant results, given in OSED Eeport 5686,- 
indicate that the recommended acceptance test for 
hookup wires as an accelerated test procedure compares 
favorably with long-duration exposure under simulated 
tropical conditions. On the basis of the method of 
rating which was adopted in evaluating the perform- 
ance of test wires, the same wires which were judged 
to be satisfactory by use of the recommended accept- 
ance test were also satisfactory after an exposure for 
one year in a tropical house. Likewise, wires which 
were rated as unsatisfactory by the acceptance test 
were also rated unsatisfactory after the one-year ex- 
posure in the tropical house. 

In order to determine the extent to which the rec- 
ommended acceptance test might give consistent re- 
sults when used by different investigators, cooperative 
tests in which five other laboratories participated were 
arranged. These tests were performed on eleven dif- 
ferent treated and untreated types of hookup wires 
which were furnished to the participating laboratories. 
One of the participating laboratories was the Tropical 
Test Station in the Panama Canal Zone. In order to 
obtain further comparison each laboratory tested the 
same wire samples according to the test methods re- 
quired by Signal Corps Specification 7 1-22 02 A and 
the JAN Specification C-76. The general conclusions 
and comparisons of the results of these cooperative 
tests are also given in OSED Eeport 5686.^ From the 
analyses of the data obtained, it is indicated that the 
acceptance test recommended by TDAC showed great- 
er agreement in results from various laboratories and 
better correlation with tropical behavior than did the 
other two test methods which were used. It was ap- 
parent from these analyses that none of the three 


64 


COORDINATION OF TEST METHODS 


methods was free from discrepancies as measured in 
terms of exact correspondence with tropical exposure. 
It is conceivable that such discrepancies result in part 
from inexact criteria of rating samples, since border- 
line cases must be rated in one or the other of two 
classes with reference to the ability of the specimen 
to support fungus growth. On the other hand, such 
discrepancies indicate that further investigation is 
needed before strict evaluation of the fungus resistance 
of these materials can be made in terms of actual 
tropical exposure. 

^ Coating Materials 

The laboratory investigations which served as the 
basis for a recommended acceptance test for coating 
materials are given, as well as the method itself, in 
OSRD Report 5687.^ In this report it is indicated that 
differences in function between hookup wires and 
coating materials, such as lacquers and varnishes, 
make it impractical to use the same method in testing 
the fungicidal resistance for both classes of these 
materials. Tests of hookup wires on which lacquers 
or varnishes may have been applied evaluate the per- 
formance of the materials of the wire in combination 
with any fungicidal or coating treatment which may 
have been given to the wire, whereas tests of coating 
materials as such should be made so as to evaluate 
the fungus resistance of only the lacquer or varnish. 
The recommended procedure for the testing of hookup 
wires was followed in the recommended test for coat- 
ing materials but with modification to provide a suit- 
able inert surface and base which would not influence 
the performance of the coating material itself. 

The major problem in developing this test method 
for coating materials lay in the selection of the inert 
base to which the coating material would be applied. 
For this purpose, tests were conducted in which vari- 
ous coating materials were applied to glass fabrics. 
Alter paper, and glass cords. On the basis of the de- 
tailed results which are given in OSRD Report 5687,^ 
glass cord was selected for various reasons as the most 
suitable base on which the coating lacquer or varnish 
might be applied in the test for fungus resistance. The 
modification of the test method for hookup wires in 
which coated glass cord serves as the test specimen is 
given in Appendix of OSRD Report 5687.^ Data are also 
presented in the report which indicate that laboratory 
results obtained by use of this method compare favor- 
ably with the results of the exposure of coated glass- 
cord samples to the natural conditions of the tropics. 


Plastics 

The lack of any references to the tropical deteriora- 
tion of plastics in the open scientific literature through 
1944 is indicated in Chapter 5. This fact, as well as 
the fact that only meager information has become 
available since, led to the recognition that a laboratory 
method suitable as an acceptance test for plastics to 
be used in the tropics was highly desirable. In their 
early deliberations the Subcommittee on Synthetic 
Resins, Plastics, and Plasticizers recommended that 
such a test be developed, and discussed the problems 
involved in such a test with the Subcommittee on 
Coordination of Test Methods. Laboratory investiga- 
tions basic to such a test method were undertaken and 
the results of these studies guided the subcommittee 
in the preparation of a test method for determining 
the resistance of plastics to fungus attack. These labo- 
ratory investigations are summarized in detail and the 
recommended test method is also given in OSRD 
Report 5688.^ 

Prior to the initiation of specific studies pertinent 
to the development of a test method for plastics, it 
was arranged that a series of plastic samples in which 
one ingredient was varied at a time be tested at the 
University of Pennsylvania. These samples were pre- 
pared by the Bakelite Corporation in conjunction with 
studies which they were conducting for TDAC, and 
for these tests a duplicate set of their experimental 
plastic formulations was furnished. These original 
tests served as a background and a point of departure 
in the investigations related to development of a test 
method for plastics. The specific formulations of the 
test sample are given in OSRD report 5688“* and 
OSRD Report 5683''^ prepared by the Bakelite Corpo- 
ration for TDAC. 

The detailed results of the exposure of these plastic 
samples for three months in a tropical house and for 
35 days on a mineral salts agar are given in OSRD 
Report 5688.^ In general, the results show that incuba- 
tion on mineral salts agar for 15 days gives rather 
close correspondence with exposure in the tropical 
house for three months. The importance of a test 
period of adequate duration is indicated by the fact 
that 18 samples which showed slight growth, if any, 
after incubation on mineral salts agar for 15 days, 
showed moderate to heavy growth after incubation of 
35 days. 

In an attempt to determine whether quantitative 
methods would be more accurate than visual rating in 
evaluating the significance of fungus attack on plas- 


TEST-METHOD STUDIES 


65 


tics, a few selected samples from this experimental 
series were oven-dried and carefully weighed, and then 
these were subjected to fungal attack on mineral salts 
agar for 35 days, after which they were again oven- 
dried and weighed. Some samples showed as much as a 
4 per cent loss in weight, but this weight loss was not 
correlated with the occurrence of fungus growth. In 
the report of this experiment it is commented that 
the criterion of weight loss would not be significant 
for all plastics in so far as functional aspects of the 
materials are concerned. x4dditional test methods, 
such as a soil-contact method, a soil-suspension 
method, and use of a nutrient medium with and with- 
out pre-inoculation, were tried in testing selected plas- 
tics but with all of them the results were considered 
as unreliable. 

Study was also made of various methods of inocula- 
tion of test samples of plastics as well as the effect of 
nutrients added to the spore suspension with which 
the test samples were inoculated. Further, informa- 
tion was obtained on the comparative fungus develop- 
ment on smooth surfaces versus sanded surfaces and 
on smooth or molded edges versus cut edges. Slight 
depressions were also drilled in the smooth surfaces 
of one set of the samples for this experiment. On only 
one sample was there any marked difference between 
growth on cut edges versus growth on molded edges 
and this same sample was the only one which showed 
any greater growth on drilled depressions than on 
molded edges. In only a few instances did the sanded 
surface develop any greater degree of growth than 
did the smooth surface. Wherever any great differ- 
ence occurred between growth on the surface and 
growth on the edge, the greater growth occurred on 
the edge. It seems that the most likely explanation for 
this is the fact that at the junction of the sample and 
the culture medium one or more physical factors may 
contribute to produce the most ideal conditions for 
fungus development. On the basis of these results it 
would appear to be unnecessary to cut samples or to 
otherwise expose internal areas, but this factor de- 
serves to be checked further. 

The test method recommended for determining the 
resistance of plastics to fungus attack is given in the 
Appendix of OSED Eeport 5688.^ The set of samples 
identical with those tested by use of the recommended 
method were exposed at the Panama Test Station for a 
period of seven months and the results obtained from 
this tropical exposure of plastics agree rather closely 
with those obtained by use of the recommended labo- 
ratory method. It is interesting that in the tropical 


exposure test there is more evidence than in the labo- 
ratory test that growth on cut or broken edges may 
exceed that which occurs on unbroken surfaces. A 
sample of phenolic fiber sheet showed complete over- 
growth on all cut surfaces but only partial growth on 
other surfaces. In the laboratory tests, however, all 
surfaces were equally affected. OSED Eeport 5688^ 
points out in conclusion that further attention should 
be given to evaluation of growth on the edge of a plas- 
tic test sample. A refinement or modification of in- 
terpretation of this growth is needed to clarify the 
situation. It is also pointed out that there is a distinct 
need for functional tests of plastics in order to obtain 
more precise criteria for evaluating the degree of de- 
terioration which occurs. This report also concludes 
(as pointed out in Chapter 5) that further correla- 
tion is needed between laboratory testing of plastics 
and field testing in the tropics, and that because of 
the complex nature of plastics an extensive study of 
plastics with respect to susceptibility to fungus attack 
is needed by laboratory test methods as well as field 
exposure methods under the natural conditions of the 
tropics. 

Biological Factors in Determining 
Fungus Eesistance of Plastics 

In addition to the studies conducted by the Bake- 
lite Corporation referred to in Chapter 5, which con- 
cerned the ability of different plastic ingredients and 
formulations to support fungus growth, a study was 
made of various biological factors influencing the 
growth of fungi on plastics with the immediate goal 
of improving the method of testing fungus resistance 
under laboratory conditions and at the same time add- 
ing to the general basic information on the subject. 
The acceptance test method referred to previously was 
followed except where certain test procedures were 
under consideration. Particular attention was given to 
the various effects of specific methods of inoculation 
and comparison of the growth of 33 different fungi 
when applied singly or in various combinations of 
mixed cultures. The results of these studies are given 
in detail in OSED Eeport 5683® and are summarized 
as follows: 

1. A study was made of various biological factors 
influencing the growth of fungi on plastics. Some 32 
different cultures of fungi representing 20 species were 
used. The fungi were for the most part isolated from 
material attacked in the tropics and the major sources 
were the Australian Mycological Panel, the British 
Ministry of Supply, and the IT. S. Department of 


66 


COORDINATION OF TEST METHODS 


Agriculture. Most organisms recommended for inocu- 
lation tests by the Australian and British authorities 
and by TDAC were included. 

2. The three representative plastics chosen were 
the vinyl chloride acetate copolymer ATnylite VU 
1900 and Vinylite VU 5904, and the phenol formal- 
dehyde cloth-base laminate Laniicoid 6030. 

3. In general the TDAC recommended method of 
testing was followed except when the various test 
procedures were under consideration. One-inch squares 
of the plastics on standard mineral salts agar in petri 
dishes were inoculated. The extent of growth ranging 
in five classes from none to very heavy was given 
numerical ratings of 0, 1, 4, 10, and 20. To date over 

3.000 petri dish culture observations have been made. 

4. Inoculation by atomization under a hood reduced 
contamination as compared to inoculation by the 
drop method, presumably because of greater com- 
petition furnished by the widely distributed inoculant 
spores. The former method is accordingly recom- 
mended. 

5. The amount of growth is dependent on the con- 
centration of the spore suspension inoculum up to 

2.000 spores per sq in. of plastic surface. Furthermore, 
the growth of contaminants is reduced as the amount 
of inoculum is increased. Single and mixed culture 
inoculations should be standardized as regards spore 
concentration, a minimum of 4,000 per sq in. per 
fungus is suggested, while 100,000 to 1,000,000 would 
be preferred for reducing contaminant growth. 

6. Since a given fungus culture under standard 
conditions tends to produce the same quantity of 
spores, a constant dilution factor may be used in pre- 
paring the standard inoculum. The different fungi 
studied varied in their spore yields per test tube cul- 
ture from 10,000 to 1,000,000,000. 

7. Observations were made at 5, 10, 20, and 40 
(lays after inoculation. Most inoculant fungi reach a 
peak of growth within this period; a few, however, 
continue to maintain a high level of growth. Most con- 
taminants reach their peak of development later than 
the inoculants. 

8. Comparisons were made of the growth of the 
different fungi in single eulture on the plastics. The 
various fungi showed diverse properties, some grow 
well on all three plastics, some on only one or two, 
some on none. In general, the greater the growth of 
inoculant, the less the growth of contaminants. Some 
fungi reach an early peak of growth and die off; this 
is more or less typical of the Penicillia. The Asper- 
gill! as a group show more sustained growth. On the 


l)asis of relative amount of growth and freedom from 
contamination the fungi were rated in five classes as 
to desirability as test organisms in single culture. 

9. Contaminating fungi were identified in as far as 
feasible and their relative abundance noted. For the 
most part they consisted of the more active genera 
carried in pure culture. Only one new species, provi- 
sionally identified as Aspergillus fumigatus, was 
observed. 

10. Several series of mixed cultures were studied. 
One was composed of TDAC recommended organisms, 
a second of the British cultures, a third of the remain- 
ing fungi, and a fourth of all the cultures. Marked 
differences were noted ; most fungi behaved as in single 
culture but a few were unable to meet mixed culture 
competition. The dominant organisms in descending 
order for the fourth series of all fungi were : VU 1900 
— Fenicillium spp., Aspergillus flavus, and Curvularia 
lunaia; VU 5904 — Penicillium spp. ; Lamicoid 6030 — • 
Cliaeiomium glohosum, Memuoniella ecliinata, Metar- 
rhizium gl utinosum , Penicillium spp., Curvularia lu- 
nata, and A. flavus, Of minor importance on all 
three plastics was Jlhizopus nigricans, A. ustus, and 
especially A. nigricam. 

11. Further single and mixed culture studies now 
in progress support the above point to the specific 
dominance of Fenicillium luteuni 41, Aspergillus {fu- 
migalus?) BTl, and A. flavus 3. 

12. Mixed cultures are recommended for general 
testing. On the basis of this study to date, the follow- 
ing organisms are considered most desirable for mixed 
culture inoculations of plastics and plastic components : 

Penicillium luieum 41 

. 1 spergillus ( fu miga lus f ) BTl 

Chaelomiuni glohosum 1042.4 

M emnoniella echinala 2 

For a wider selection, the following may also be 
included : 

Penicillium sp. 1336.2 

Aspergillus flavus 3 

Curvularia lunaia 46 

Meiarrhizium gluiinosum 1334.2 

8.2 4 Pure Culture Methods for 

Testing Textiles 

Certain of these studies were undertaken as a result 
of decisions which were made during a Conference on 
Biological Testing and Test Organisms which was 
arranged and sponsored by TDAC,'’’ particularly those 
studies on the effect of the nature and composition of 


TEST-METHOD STUDIES 


67 


culture media on textile deterioration by microorgan- 
isms and those involving a comparison of strains of 
Aspergillus niger for textile testing. A comparison 
of cellulose degradation by two species of Cliaetomium 
was also made. The investigations of sterilization 
treatments in pure culture studies of textile deteriora- 
tion by microorganisms were the outgrowth of co- 
operative tests with the American Association of Tex- 
tile Chemists and Colorists to determine the reproduci- 
bility of various textile testing procedures. The results 
of these studies are given in OSRD Eeport 5689.^ 

In addition to studies, the nature of which is in- 
dicated above, limited experiments were conducted to 
determine the relation of hyphal penetration of fabric 
fibers to loss in tensile strength which occurs in fab- 
rics when they are exposed to fungus attack. The ob- 
servations which were made strongly suggest that 
fungus deterioration of cloth is not always directly 
related to the hyphal penetration of fibers. In some 
instances, particularly in young cultures, it appeared 
that fibers with breaks in their walls contributed to 
loss in breaking strength of the cloth in which there 
was seldom any penetration of the hyphae into the 
lumina of the fibers. This suggests the possibility that 
some textile breakdown, following inoculation, may 
result from a digestion process by enzymes or other 
secretions of the hyphae in contact with the fiber sur- 
face. Studies on this aspect of fabric deterioration 
which were conducted at the Philadelphia Quarter- 
master Depot,® however, have led to a different inter- 
pretation in that they suggest that the period of rapid 
decline of tensile strength, after the penetration of 
the fiber wall by the fungus hyphae, corresponds with 
the period of rapid growth of fungus in the lumina of 
the fibers, and that enzymatic action on the exterior 
of the fiber presumably accounts for very little of the 
total decline of fiber strength. It is obvious from these 
conflicting interpretations that further information 
is needed on this point. 

In the report of the Conference on Biological Test- 
ing and Test Organisms, the discussion which centered 
around the use of different media in pure culture 
textile tests is recorded. In practice, presumably stand- 
ard media as used by different laboratories have been 
modified slightly to give rise to considerable variations 
in results and conclusions. A comparison made of the 
basic media used in various laboratories for pure cul- 
ture microbiological tests revealed that, for a given 
incubation period, standard organisms produced vary- 
ing reductions in breaking strengths of textiles when 


tested upon the different media, notwithstanding the 
use of a generally standardized technique. This in- 
dicates that, for purposes of standardizing exposure 
trials of fungicidal treatments, there should be proper 
selection of the basic agar medium in pure culture 
tests, inasmuch as pure culture tests are widely used 
in laboratory trials of fungicidal treatments. The 
conditions which particularly influence a variation 
in results are whether or not a carbon source was sup- 
plied (maximum yegetative growth with little or no 
deterioration of cloth usually occurred in the presence 
of a carbon source), the pH of the medium (somewhat 
greater losses in breaking strength occurred on the 
more alkaline substrates), and the nitrogen supply in 
the nutrient medium. 

The Conference on Biological Testing and Test Or- 
ganisms decided that a comparison of the strains of 
Aspergillus niger for textile testing was desirable, 
particularly since many different strains of the organ- 
ism had been used in various types of testing and be- 
cause evidence was available that at least some of these 
strains differed in their physiological properties. Cer- 
tain specifications require materials to pass tests in 
which Aspergillus niger is used but they do not 
specify a particular strain, and it was visualized that 
these studies would indicate the desirability of using 
specific strains and give an indication as to which 
strains were more suitable for textile testing purposes. 
In all, fourteen different strains of the organism were 
acquired for these comparative studies. Investigations 
of the resistance of the strains to fungicides were made 
with the fungicides incorporated into fabrics and with 
the fungicides incorporated into the culture media. 
The ability of the various strains to decompose cellu- 
lose was determined as was their ability to compete 
with other organisms. The results as recorded in 
OSBD Deport 5689'^ show that the different strains did 
not vary markedly in their tolerance to fungicides 
except for two strains which were also less aggressive 
in competition with contaminating organisms and 
produced only meager sporulation. This pertains to 
studies with fungicides incorporated into fabrics. 
Greater variability was seen among the various strains 
where fungicides were incorporated directly into the 
agar and some strains characteristically produced 
variants under these conditions. In general, one strain 
exceeded all others in effecting reductions in tensile 
strength of gray cotton duck in several inoculation 
procedures. No strains were particularly aggressive 
in competition with other fungi in cultures and those 


68 


COORDINATION OF TEST METHODS 


strains which were least tolerant to fungicides incor- 
})orated in the fabrics showed little or no growth at 
all under these conditions. 

Tn the studies concerning the ability of species of 
Chaetomium to degrade fabrics in pure culture tests 
there were no significant differences among four 
strains of C. glohosum, and a strain of C. elatum ap- 
peared less effective than any of the strains of C. 
glohosum in the experiments conducted. 

In pure culture tests of fabrics on mineral salts 
media, aseptic conditions are rigidly maintained dur- 
ing inoculation and incubation procedures. The ster- 
ility of the cloth, however, may or may not be ignored. 
Various undesirable conditions result when contam- 
inating organisms present on the fabrics develop and 
these may affect the results of the tests. If sterilization 
of the test cloth is to be followed, the cellulose and 
other constituents of the fabric should not be altered ; 
the cloth should be as susceptible to the effects of the 
test organisms before and after treatment ; where 
treated cloth is used, the effect on test fungi must not 
be changed by sterilization; and any disinfecting 
agents should be easily removable from the cloth so 
that the test organisms are not affected. 

The tests which Avere conducted in these investiga- 
tions employed two methods of sterilization: (1) 
chemical sterilization through the use of volatile fun- 
gicides which Avere easily removed from the fabric be- 
fore inoculation and AAdiich did not enter into direct 
chemical combination Avith any ingredient of the 
cloth; and (2) physical sterilization such as by steam 
or dry heat. The experiments described in OSED Ee- 
port 5681V concern the use of formaldehyde and methyl 
alcohol as A^olatile fungicides. So far as chemical steri- 
lization is concerned, it Avas found that the length of 
the exposure required to insure complete sterilization 
AA^as generally prohibitively long to Avarrant the use of 
such agents as a means of sterilizing cloth for inocu- 


lation tests. Formaldehyde Avas retained by the cloth 
for long periods and excessively long aerating times 
AA'ould be required to thoroughly remove the last traces 
of disinfectant before inoculation tests could be per- 
formed Avithout danger of interference Avith the test 
organisms. Cloth sterilization Avith steam under pres- 
sure appeared to offer the most satisfactory practice 
for routine use. Small reductions in tensile strength 
did occur after autoclaving and in inoculation tests a 
trend AA^as indicated for fungus deterioration of the 
cloth to become someAvhat reduced Avith increasing 
exposure to the steam sterilizing conditions. 

8.2.5 Evaluation of Tests Results in 
Terms of Field Performance 

The ideal test method to determine Avhether or not 
a particular item of military equipment or material is 
suitable for tropical service is to expose the item to the 
natural conditions of the tropics as a final test. It is, 
hoAA^ever, obviously impossible to do this except per- 
haps in a feAV cases, particularly in time of Avar; con- 
sequently, reliance must be placed on accelerated tests 
AA^hich have been shoAvn to correspond to much longer 
periods of tropical service. In only a very feAv instances 
have beginnings toAvard this goal been possible, even 
Avith the increased testing program during World 
War II, and the necessary investigations to relate 
these accelerated tests to performance in the tropics 
still remain to be performed in most instances. The 
necessity for further studies to standardize and refine 
the various test methods used in laboratory studies on 
the prevention of tropical deterioration are indicated 
for many materials, and maximum benefit of such 
improved methods can only be derived AAdien they 
haA^e been adequately correlated Avith exposure to 
natural conditions of the tropics. 


Chapter 9 

RESULTS OF TESTING MATERIALS UNDER 
TROPICAL CONDITIONS 


9 1 LOCATION OF TROPICAL 

TEST STATION 

I N THE TESTING PROGRAM of the Tiopical Deteriora- 
tion Administrative Committee [TDAC], exposure 
of materials to the natural conditions of the tropics 
has been made in connection with fundamental studies 
on the deterioration of fabrics which are discussed in 
Chapter 4 and in studies on the prevention of tropical 
deterioration of optical instruments which are dis- 
cussed in Chapter 3. These exposure tests of optical 
instruments constituted field trials of the most prom- 
ising methods for protecting the instruments. Trop- 
ical testing was not limited to those studies cited 
above, however, and the results of tropical exposure 
tests of a wide variety of other materials are summar- 
ized in the following sections. 

The tropical exposure testing was performed under 
natural conditions at Barro Colorado Island, Panama 
Canal Zone, and under simulated tropical conditions 
in a specially constructed tropical house in which tem- 
perature and humidity could be closely controlled at 
the L^niversity of Pennsylvania. Section 9.2 will deal 
with the results of exposure tests in Panama, and 
Section 9.3 discusses the results of the exposure test- 
ing in the tropical house at the University of Pennsyl- 
vania [UP]. Limited testing using balanced mite- 
fungus populations was performed at the University 
of Pittsburgh and Section 9.4 deals with the results 
of these exposure tests. 

The Tropical Test Station was established at Barro 
Colorado Island situated in Gatun Lake, Panama 
Canal Zone. This island was set aside as a biological 
reserve in 1923 and has since been established as the 
Canal Zone Biological Area by an Act of Congress. 
The facilities of Barro Colorado Island were made 
available to TDAC by the Board of Directors of the 
Canal Zone Biological Area. A description of this test- 
ing station is given in OSRD Report 5690^ along with 
information on the rainfall, relative humidity, and the 
fauna and flora, particularly fungi, of the region. 
The report describes the laboratory facilities which 
were available and the nature of the exposure facilities. 
There were established a sun-exposure site, a shade- 


exposure site, an open jungle shed, a closed storage 
shed, and a jungle-exposure pen; the contrasting con- 
ditions which these different sites offer are presented 
in this report. 

The Tropical Test Station was established by UP 
in conjunction with their studies on the prevention of 
deterioration of optical instruments, but it was soon 
realized that by the use of these facilities for the ex- 
posure of other materials, valuable information could 
be obtained. Accordingly, invitations were extended 
to offices of the Army and Navy to submit material 
for exposure at the station. All arrangements were 
made through TDAC, and the results of the expo- 
sures were in turn made available to the submitting 
offices by the committee. The summaries of results 
which are given below have not been previously re- 
ported, except in a few instances. In all, a total of 
over 15,000 individual items were exposed in Panama. 

92 RESULTS OF EXPOSURE TESTS 
IN PANAMA 

In the following discussion of tests, those items such 
as textiles or packaged materials which were sent to 
the station for exposure and return to the submitter 
are not indicated. 

Flying Clothing Material 

These materials were submitted by the Aero-Medical 
Laboratory of the Air Technical Service Command 
and included fourteen different samples of various 
types of fabrics and leather materials. These were ex- 
posed in a roofed jungle-exposure chamber for a 
period of eight months. At the end of the exposure 
period samples of Nylon, waterproofed boat cloth, 
and alpaca wool pile were generally in the best con- 
dition and showed little or no fungus growth. Samples 
of sheep shearling, collar fur, and cowhide showed 
considerable fungus development on both the leather 
and fur surfaces. The rayon and cotton fabrics all 
showed fungus development in varying degrees. None 
of these materials were given fungicidal treatment. 


69 


70 


TESTING MATERIALS UNDER TROPICAL CONDITIONS 


Coated Airplane Fabrics 

These materials were submitted by the National 
Bureau of Standards in conjunction with work for 
the Bureau of Aeronautics, Navy Department, and con- 
sisted of 1,768 samples wbicb were to be exposed above 
ground in sunlight, above ground in shade, on the sur- 
face of the soil, and buried in the soil. Three sets of 
eight strips each of seventeen different mildew-proof- 
ing treatments were supplied for each exposure con- 
dition, in addition to one set to be used for initial 
breaking-strength determinations. Evaluations con- 
sisted of breaking-strength measurements supple- 
mented by visual observations. The results of this 
study were summarized informally for the Subcom- 
mittee on Synthetic Resins, Plastics, and Plasticizers.^ 
The test fabrics were coated with four coats of clear 
cellulose acetate butyrate airplane dope and two coats 
of camouflage white pigmented airplane dope in ac- 
cordance with specifications pertaining to coated air- 
plane fabrics. Six different fungicides were applied 
in two concentrations by incorporating them in the 
first coat of doping, the other five fungicides were ap- 
plied to the fabric by the fungicide manufacturer 
prior to the application of the doping. Only slight 
changes in tensile strength were noted in the samples 
exposed in air in the shade. On the other hand, marked 
losses in tensile strength occurred in the samples ex- 
posed in the air in sunlight. Part of this loss is to 
be ascribed to deterioration of the highly pigmented 
camouflage Avhite dope and concomniitant loss of its 
light-screening properties. The largest loss occurred 
in the two samples in which copper naphthenate had 
been incorporated into the first coat of dope. Relatively 
large loss in tensile strength was shown by the samples 
treated with phenyl mercuric salicylate. The smallest 
loss in sun exposure was shown by the zinc dimethyl- 
dithiocarbamate sample with the higher concentration 
of the fungicide. 

Of the samples exposed on the soil surface, those 
treated with phenyl mercuric salicylate showed good 
retention of strength. Only a slight change in strength 
was noted for the control sam|)lcs containing no fun- 
gicide but those treated with dihydroxydichlorodi- 
phenylmethane showed a marked tensile-strength loss. 
Fabrics treated with phenyl mercuric salicylate, the 
TTarodite process, and zinc dimethyldithiocarbamate 
showed the best strength retention. 

Examination of the fabrics returned from Panama 
showed that no fungicidal treatment altered the ad- 
hesion between dope and fabric except those samples 


treated with copper naphthenate and exposed to sun 
and soil burial and those treated with zinc naphthe- 
uate exposed to soil burial. On the basis of these re- 
sults, recommendations were made to the Bureau of 
Aeronautics that zinc dimethyldithiocarbamate be 
used as the mildew-proofing compound for coated air- 
plane fabrics. 

Packaged Fruit Bars 

In addition to the 800 individual bars which were 
sent to Panama for exposure tests, the same luimbcr 
was sent to the University of Pittsburgh and UP 
for exposure under artificial tropical conditions. The 
results summarized here are taken from data from 
all the exposures. 

The samples were submitted by the Packaging Sec- 
tion, Military Planning Division, Office of the Quar- 
termaster General, and they consisted of 2-oz fruit 
bars double wrapped in various combinations of regu- 
lar untreated cellophane and cellophane which had 
been given a special carbon-silver coating, with and 
without pasteurization after the first wrapping. The 
carbon-silver coating had been shown to have fungi- 
cidal value in preliminary tests and the object of these 
exposures was to determine its value in protecting 
such a highly susceptible material as a fruit bar from 
microbiological attack. 

The observations which were made included visual 
observations on the extent of mold development, and 
the occurrence of swelling and bleeding at the seams, 
in addition to weight determinations which indicated 
the amount of moisture transmitted through the 
wrappings. Conclusions with reference to the value 
of the fungicidal coating are as follows: 

1. The carbon-silver coated cellophane offered no 
appreciably better resistance to fungi than did the 
regular cellophane. 

2. The moisture-vapor I’csistance of the celloidiane 
was lowered in coating it with the carbon-silver mix- 
ture. 

3. Pasteurization degraded the moisture-vapor re- 
sistance of the regular cellophane to a greater degree 
than that of the coated cellophane. Some evidence was 
obtained which indicated that the heat of pasteuriza- 
tion effected a more efficient seal of the inner wrapper. 

4. The best combination of wrappings, therefore, 
consisted of an inner Avrapping with the coated cello- 
phane, folloAved by pasteurization before the outer 
wrap of regular cellophane was applied. 


RESULTS OF EXPOSURE TESTS IN PANAMA 


71 


Cases of Shoes with and wiriiouT 
Volatile Fungicides 

Four oases of shoes, two with fungicidal pellets and 
two without such pellets, were submitted by the Foot- 
wear and Leather Section, Military Planning Division, 
Office of the Quartermaster General. The volatile 
fungicide contained in the pellets was trichlorophenol. 
Two of the boxes, one with and one without fungicide, 
were opened by error upon arrival at the exposure 
station. After three months’ exposure in a roofed 
chamber, no mold was evident on the shoes in any of 
the boxes. Exposure was continued for three addi- 
tional months in an open jungle pen with the boxes 
elevated for protection against termites. At the end 
of this additional three-month exposure, the two car- 
tons with and without fungicide which were unopened 
did not show any development of fungus on the shoes. 
However, in the two cartons which had been opened 
by error, all of the 24 pairs of shoes in each carton 
showed at least some fungus growth on the stitching 
in addition to fungus in varying amounts on the 
leather itself. 

Stitched Leathee Samples 

Each sample consisted of two small pieces of heavy 
leather stitched together along one edge. Ten different 
thread treatments, including an untreated control, 
were represented by six repetitions of each treatment. 
These were submitted by the Footwear and Leather 
Section, Military Planning Division, Office of the 
Quartermaster General. 

After 8 weeks’ exposure in an open jungle cham- 
ber, where they would be exposed to maximum wetting 
and drying, the samples were broken on a Scott Break 
Tester. At the end of this period slight visible fungus 
growth appeared on all the samples, except one set con- 
taining Nylon thread. The fungi seemed to be mostly 
species of Penicillium and the growth did not extend 
appreciably onto the leather. 

The breaking strengths for one-half of the differ- 
ent treatments were greater than the capacity of the 
machine, and these were returned to the submitting 
office. All of the fungicidally treated samples of thread 
showed a greater average breaking strength than the 
untreated control. Those treatments which were only 
slightly stronger than the control employed Rohm and 
Haas fungicide H-3258 and a special treatment with 
copper naphthenate. In addition to the Nylon thread 
sample, the other treatments which were markedly 


stronger than the untreated control were tetrabrom 
orthocresol, phenyl mercury triethanol ammonium 
lactate, a copper naphthenate treatment, M. fungicide 
(Arkansas Company) , dihydroxydichlorodiphcnylnic- 
thane, and Hyamine (Rohm and Haas Co.). 

Treated Filter Papers 

These materials were submitted by the Office of the 
Chief of Ordnance, in cooperation with the TDAC 
Subcommittee on Electrical and Electronic Equip- 
ment, and consisted of 30 samples of filter paper in 
five sets as follows : one set — untreated paper, one set 
— paper dip-coated with paraphenylphenol, tung oil 
varnish ; two sets with one of the following fungicides 
included in the coating varnish of each — pentachloro- 
phenol and salicylanilide ; and, one set dip-coated with 
Insl-X 25A. The specimens were exposed for a period 
of approximately seven months, and although the 
untreated samples showed slight fungus growth after 
one month’s exposure, this disappeared and at the 
end of the exposure period all samples were free of 
fungus growth. 

Sheet Insulating Materials 

The Office of the Chief of Ordnance and the Sub- 
committee on Electrical and Electronic Equipment 
submitted these materials jointly. They consisted of 
120 samples of tliree types of phenolic plastic sheet 
insulating materials. These were separated into twelve 
sets, four sets of each type of material. Initially one 
set of each was exposed in a shady and sheltered loca- 
tion, and one set of each was placed in a sunny loca- 
tion. After eight weeks the original exposure was ter- 
minated and the entire exposure was duplicated with 
the remaining samples. 

The objective of the test was to determine the extent 
of moisture uptake by each type of material under 
the contrasting conditions, and in these determina- 
tions weighings on eaeh individual sample were made 
at regular and frequent intervals. The extent to which 
the samples absorbed moisture was then compared 
with the water absorption of these same materials at 
known humidities and at a temperature of 23 C. The 
average water absorption by the Panama samples was 
generally comparable to the performance of the mate- 
rial under laboratory relative humidities of approxi- 
mately 92 to 95 per cent. Generally the shade-expo- 
sure samples showed about a 0.5 per cent increase in 
weight over the sun-exposure samples. 


72 


TESTING MATERIALS UNDER TROPICAL CONDITIONS 


Plastic Terminal Strips 

Tliese samples consisted of live sets of ten samples 
each of Jones terminal strips. One set was untreated, 
one was treated with No. 74 Bakelite varnish alone, 
and the remaining three sets were treated with the 
above varnish which contained separate fungicides as 
follows : 1 per cent phenyl mercury salicylate, 5 per 
cent pentachlorophenol, and 5 per cent salicylanilide. 
This was a joint project of the Office of the Chief of 
Ordnance and the TDAC Subcommittee on Electrical 
and Electronic Equipment. 

Frequent resistance readings with a megohm bridge 
were made at specified intervals for about 3^2 months. 
The exposure was made in an enclosed jungle-expo- 
sure chamber where the resistance measurements were 
made. 

An interim report on this tesC summarizes the re- 
sults. No fungus growth appeared on any of the speci- 
mens. The results indicate that a coating of varnish 
on such materials as these slows the rate of deteriora- 
tion by factors of 5 to 10. They further indicate that 
in these tests the pure varnishes proved to be slightly 
superior to those containing the fungicides. 

Gas Masks 

These items were exposed for the Canadian Air 
Force, and they included masks until three different 
types of face-piece lining — chamois, fabric, and un- 
lined. During the eight months’ exposure of these 
items considerable mold developed on practically all 
]iarts. There were no appreciable differences in the 
degrees to which the different types of face-piece lin- 
ings supported mold growth. No fungicidal treatment 
was given to the samples. 

Cotton Fabrics 

dJiese fabrics also were exposed for the Canadian 
Air Force; four treated fabrics and one untreated 
control were included. The duration of exposure in 
the opeii jungle was three months. Breaking strength 
values at one month showed no significant changes. 
The greatest change after three months’ exposure oc- 
curred in the untreated sample which lost approxi- 
mately 17 per cent of its original strength. This un- 
treated sample also showed the highest evidence of 
fungus growth. The best protection of the fungicides 
used was given by 1.4 per cent Puratize N5-X (phe- 
nyl mercury tricthanol ammonium lactate). 


1’aper Message Pads 

These were exposed for the Canadian Army Staff 
at the request of the Office of the Chief Signal Officer. 
Exposure consisted of storage for eight months on 
open shelves in the closed jungle-exposure chamber 
for some, and a more severe exposure in an open jungle 
pen for others. Some termite damage was noted in the 
pads on the bottom of the pile in the closed chamber. 
The only fungus development occurred to a slight 
extent on the binding and backing of pads in the open 
pen, and to a greater extent on dead insects between 
pages. Generally, those in the closed chamber were in 
excellent condition, while those in the open jungle pen 
became badly discolored with yellow, red, and green 
stains which extended throughout the pads. 

Bridged and Steel Panels of Strifpable Coaitxgs 

These samples consisted of a series of nine panels 
submitted by the Naval Ordnance Laboratory, Silver 
Spring, Maryland. Fungicides were incorporated in 
the materials before spraying but the compounds used 
were not disclosed. After six months’ exposure in the 
roofed jungle chamber, slight fungus growth was 
present on about one-half of the panels and in almost 
all cases it was associated with insect debris. In a few 
cases the fungus growth had extended out from the 
insect debris in a smaller circular area to V 2 in. in 
diameter. No prominent deterioration of the coatings 
was noted. 

Ear AVardens 

This series of materials was exposed for the Psycho- 
Acoustic Laboratory, Harvard University. The ear 
wardens were made of Vinylite which contained a 
high percentage of castor oil used as an ingredient 
of the plasticizer. Five per cent dihydroxydichloro- 
di phenyl methane was added to some of the samples 
while others were untreated. These were exposed nnder 
varying conditions — indoors and outdoors and inside 
and outside a small carrying capsule. 

After six months’ exposure fungus growth was pre- 
valent on the wardens throughout the series. Gener- 
ally, it Avas more prevalent on the treated than the un- 
treated samples. Invariably the fungus on the treated 
samples was closely appressed in an oily film which 
Avas exuded. This film did not appear on the untreated 
samples. The exuded oil film probably represented 
exuded plasticizer; therefore, in addition to being 


RESULTS OF EXPOSURE TESTS IN PANAMA 


73 


ineffective in the prevention of mold growth, the 
added fungicide promoted the exudation of plasticizer. 

A bluish coloration was noted in both treated and 
untreated ear wardens and this was attributed to a 
dye which was transferred from the carrying capsule 
to the wardens. This had previously been observed in 
the submitting laboratory and measures were taken 
to correct this by use of a pigment instead of a dye. 

PoucHETTE Containers for Ear Wardens 

These were also submitted by the Psycho-Acoustic 
Laboratory and were exposed in the roofed jungle 
chamber. The pouchettes were made of a coated fabric 
with stitching along the edges and with brass snaps. 
No corrosion of the metal occurred in the 3y2 months’ 
exposure. Surface mold appeared on the exteriors of 
all samples and within the last month mycelial growth 
appeared on the interiors of the specimens. More sur- 
face growth was present on the stitching than on the 
plastic coating. At 2^2 months, the fabric began to 
lose its pliability, and at 3V2 months this was more 
pronounced. 

Neoprene Earphone Sockets 

These items were also submitted by the Psycho- 
Acoustic Laboratory. The sockets were of two types — 
sponge neoprene with the sponge exposed, and the 
same type with a thin sheet of mechanical neoprene 
over the sponge. Exposure consisted of a three-month 
period in the roofed jungle chamber. In this period 
the sockets with exposed sponge picked up about 5 g 
of water while those with the covered sponge gained 
only about 2 g of water. This would indicate that the 
covered sponge type would probably perform much 
more satisfactorily under prolonged exposure to hu- 
midity than the uncovered type, particularly since 
excessive water absorption would result in marked 
distortion of the socket. 

Test Samples of Strippable Spray Coatings 

The Naval Ordnance Laboratory, Silver Spring, 
Maryland, submitted this series of eight test samples 
to determine whether they are susceptible to attack by 
insects or other animals. They were placed in the open 
jungle and after six months’ exposure there was no 
evidence of attack by any form of animal life. 

Glue- and Resin-Bonded Cork Samples 

Specimens of both glue-bonded and resin-bonded 
cork were treated with amyl acetate containing varying 


percentages of paranitrophenol by the University of 
Pennsylvania and for each percentage treatment of 
each type of cork there were leached and unleached 
duplicates. Studies on optical instruments (Chapter 
3) indicated the necessity for fungicidal treatment 
of cork in such equipment and in preliminary trials 
paranitrophenol proved to furnish excellent protection. 
In all fifty samples were included ; these were exposed 
for six months in the roofed jungle-exposure chamber. 

Except in the case of the leached resin-bonded cork, 
no fungus growth appeared on any of the samples 
which had 1.2 per cent or more fungicide by weight. 
No significant differences were noted between the 
glue-bonded and resin-bonded corks. These results are 
reported in OSRD Report 5684.^^ 

Glass Cord Coated with Fungicidal 
Lacquers and Varnishes 

These materials consisting of fifteen 1-yd samples 
were prepared for exposure by UP in order to obtain 
information on the performance under natural trop- 
ical conditions which could be correlated with labo- 
ratory testing procedures in the development of a 
standard test method for coating materials. The re- 
sults are discussed in OSRD Report 5687.^ 

Plastic Samples 

These materials were also exposed in conjunction 
with the UP studies on test methods in order to cor- 
relate results of tropical exposure with laboratory 
tests in the development of a standard test method for 
evaluating the fungicidal resistance of plastics. The 
results of these studies are discussed in OSRD Report 
5688.® 

Hookup Wires 

These included fungicidally treated and untreated 
wires identical with the specimens used in compara- 
tive laboratory trials of different test methods for 
evaluating the fungicidal resistance of hookup wire. 
OSRD Report 5686^ gives the results of these com- 
parative laboratory tests and contrasts these with the 
results of tropical exposure. 

The Office of Research and Inventions, Navy De- 
partment, has continued to operate the Panama Test 
Station through a contract with the UP since the 
activities of TDAC were terminated. Among the ma- 
terials which were under exposure when the Office of 


74 


TESTING MATERIALS UNDER TROPICAL CONDITIONS 


Research and Inventions assumed the contract were 
the following: a set of 8,640 treated cotton fabrics 
submitted by the Engineer Board, Fort Bel voir, Vir- 
ginia ; a set of 265 samples of treated twines, netting, 
gaskets, etc., submitted by the Bureau of Ships; and 
a set of 2,016 fungicidally treated wires, supported 
in trays, submitted by the Naval Research Laboratory. 

Only preliminary reports on these materials had 
been made prior to transfer of the Panama test sta- 
tion, but it has been the policy of the Office of Re- 
search and Inventions to continue exposure of Army 
materials, as well as Navy materials, and to make 
the results available to the submitting offices or 
laboratories. 

93 RESULTS OF MATERIALS TESTING 
BY EXPOSURE IN THE TROPICAL 
HOUSE AT THE UNIVERSITY 
' OF PENNSYLVANIA 

In connection with the studies on optical instru- 
ments at UP there was constructed a tropical house 
in which the natural conditions of the Canal Zone 
were duplicated. Temperature and humidity were con- 
trolled so as to provide a daily cycle in which conden- 
sation, so important in tropical exposure, would occur 
on test materials. Representative fungi and insects 
native to the Canal Zone were introduced to provide 
biological agents of deterioration. OSRD Report 
4048* describes the construction and operation of the 
tropical house. 

The tropical house was built while the studies on 
optical instruments were under the direction of NDRC 
Section 16.1. After these studies were transferred to 
TDAC and a broad program of tropical testing was 
undertaken, this facility was used to supplement tests 
under natural conditions in Panama. The results of 
the various tests are summarized in the following. A 
total of over 1,300 individual items were exposed in 
the tropical house. 

Lkatheu and Fabiuc Carrying Case 

This was exposed for a period of two months for 
the Engineer Board. The fabric (canvas) was treated 
according to specifications with copper naphthenate 
(solvent method) and the leather was dipped in a 1 
per cent solution of equal parts of paranitrophenol 
and parachlorophenol. The leather was extensively 
molded at the conclusion of the test. Mold was also 


present on the external fabric but not conspicuously, 
while the internal fabric surface was irregularly 
spotted with fungi. 

Glue-Cork and Packaged Cork Samples 

These materials were also exposed for the Engineer 
Board and they included 96 samples of glue-cork com- 
positions with various fungicidal treatments and 24 
samples of fungicidally treated cork packaged with 
different materials. The exposure period was two 
months. 

All of the glue-cork compositions had approxi- 
mately 75 per cent or more of their surfaces covered 
with fungi. The fungicides used were phenyl mercury 
derivatives which were applied in varying concentra- 
tions and with different solvents. 

The same fungicidal treatments were used on the 
cork which was packaged. Some methods of packaging 
were more susceptible to fungus attack than others, 
but a considerable number of samples supported abun- 
dant fungus growth — in some cases the packages be- 
came unsealed or the labels were obscured. A paraffined 
package and a metal-foil package which were opened 
showed the cork contents in excellent condition. All 
other samples were returned to the Engineer Board 
for examination. 

Ear Wardens 

These materials are the same as those exposed in 
Panama and which are discussed in Section 9.2. In 
petri dish tests wardens treated with 1, 2, and 3 per 
cent of tetrabrom orthocresol and dihydroxydichloro- 
diphenylmethane all supported fungus growth. After 
one month in the tropical house all remained free 
from fungus except 1 and 2 per cent treatments of 
dihydroxydichlorodiphenylmethane, which showed 
fungus growth near the area of contact with a shelf. 

Later, samples with 5 per cent of the fungicides 
were also tested in culture dishes on mineral salts 
agar and in the tropical house. All samples in the 
petri dish tests developed fungus growth in varying 
degrees. Those in the tropical house remained free 
from fungi after six weeks’ exposure. None of the dis- 
coloration or exudation of plasticizer which developed 
in the Panama exposure occurred with those in the 
tropical house. 

Plastic Samples 

This series of materials was prepared by the Bake- 
lite Corporation in their studies on plastics for TDAC 


RESULTS OF EXPOSURE TESTS AT UP TROPICAL HOUSE 


75 


and the ingredients were varied one at a time. Viny- 
lite was the basic plastic present in all the samples. 
The detailed results with reference to the extent which 
these materials supported fungus growth after three 
months’ exposure in the tropical house are given in 
OSRD Report 5688.® The results of the tests conduct- 
ed by the Bakelite Corporation on the same series of 
samples are given in OSRD Report 5683.® 

Leathek from Japanese Shoe 

This sample was taken from an unused shoe in stor- 
age. After six weeks’ exposure abundant fungus 
growth was present on the stitching, and could be de- 
tected microscopically on extensive areas of the 
leather. However, macroscopically the leather appeared 
in relatively good condition. Chemical analysis by the 
National Bureau of Standards did not reveal any fun- 
gicidal treatment. It was further indicated that the 
leather contained but little grease and that a catechol 
tanning material was used, therefore little nutrient 
was available to support fungus growth. 

Polaroid Lenses 

The Bureau of Medicine and Surgery, Navy Depart- 
ment, submitted these lenses, which were exposed for 
six weeks. The polarizing lenses were of laminated 
cellulose acetate composition. Fungus growth associ- 
ated with organic detritus occurred on the lens surfaces 
without damage to the lenses. When the lenses were 
placed on the floor of the tropical house, considerable 
separation of the laminations occurred with fungus 
abundant on the inner surfaces of the laminations. 
Such a test as this is, of course, much more severe than 
the conditions which the lenses would be expected to 
meet in use, and it would normally be expected that 
no fungus damage or separation of elements would 
occur. 

Seat Cushion Assembly 

This item was submitted by the Office of the Chief 
of Ordnance; no fungicidal treatments were applied 
to any portion of the assembly. The more obvious de- 
velopments after eight weeks’ exposure were the exten- 
sive warping of the plywood bottom, pronounced rust- 
ing of tacks, and heavy mold over rather large areas 
of the leather covering. Stitching threads also sup- 
ported heavy mold growth. 

Coated Lenses 

These consisted of 40 lenses which were coated with 
clear lacquers as follows: ethyl cellulose plus 5 per 


cent Cresatin, ethyl cellulose plus 1 per cent Merthi- 
olate, Vinylite lacquer S-986,Dulac lacquer 86 A. These 
were prepared in conjunction with the program of the 
TDAC Subcommittee on Optical Instruments. After 
two weeks’ exposure with the lenses supported on glass 
rods so as to avoid contact with organic materials, the 
Merthiolate-treated lenses and about half of the lenses 
coated with Dulac lacquer were free from fungus 
growth. Practically all of the remainder showed fungus 
growth in varying degrees. During an additional two 
weeks’ exposure organic material was allowed to come 
in contact with the lenses and four of the ten for- 
merly fungus-free Merthiolate-treated samples devel- 
oped fungus growth. None of the other treated lenses 
were free from mold, and all those Cresatin-treated 
showed heavy growth. Those coated with Vinylite lac- 
quer developed considerable blistering and cracking 
in the coating. 

Another series of lenses coated with similar mate- 
rials (ethyl cellulose, Vinylite, VYHH, and cellulose 
acetate, each with 1 per cent Merthiolate (free acid), 
and Dow-Corning Resin No. 2012 in a surface lacquer) 
gave similar results after six weeks’ exposure. They 
all supported fungus growth to a slightly greater ex- 
tent, but the samples were in contact with decaying 
organic material throughout the period of test. Al- 
though the Vinylite-coated samples showed the great- 
est development of fungi, there were no moisture ef- 
fects of the coating as in the other coatings. 

Vellumoid Gaskets 

These were also prepared in conjunction with the 
program of the TDAC Subcommittee on Optical In- 
struments. They consisted of ten samples, some of 
which were untreated, some soaked in alcoholic Mer- 
thiolate (free acid) solution only, and some coated 
with ethyl cellulose plus Merthiolate (free acid) after 
soaking. After five weeks those which were untreated 
showed extensive mold development, but all of the 
treated samples were free from mold. 

Coated Projection Screen Samples 

These were submitted by the Pictorial Engineering 
Research Laboratory, Signal Corps Photographic Cen- 
ter, and consisted of samples of commercially available 
projection screen materials. These samples were in- 
oculated with a spore suspension before placement 
in the tropical house. After two weeks, abundant to 
heavy growth was present on all of the samples, with 
slight to severe stains apparent on the white surfaces. 


76 


TESTING MATERIALS UNDER TROPICAL CONDITIONS 


A subsequent set of samples of other screen mate- 
rials, some of which had fungicides incorporated in 
the coating, were exposed for 28 days. Fungus growth 
generally did not develop to as great an extent, nor 
was staining as widespread. Breaking-strength deter- 
minations did not reveal a significant loss of fabric 
strength in the short period of exposure. The samples 
were returned to the submitting laboratory for white- 
ness and brightness tests, but information concerning 
the results of these tests was not received. 

Tkeated Leather Cases 

Three leather cases with different fungicidal treat- 
ments were submitted by the Pictorial Engineering 
Research Laboratory, Signal Corps Photographic Cen- 
ter. Two of them were given the treatment indicated 
in Ordnance Department Specification AXS-1416. 
This calls for a mixture of salicylanilide, isopropyl 
alcohol, wax, and dry-cleaning solvent in specific pro- 
portions. With one case the wax was omitted. The 
other case was dipped in a 1 per cent solution of San- 
tobrite. After 21 days’ exposure the salicylanilide- 
treated cases showed only very slight growth of fun- 
gus, while the other showed abundant fungus spotting. 

Felt Samples 

This miscellaneous lot of different kinds of felt was 
also submitted by the Pictorial Engineering Research 
Laboratory, Signal Corps Photographic Center. Fun- 
gicidal treatments applied to some of the samples were 
effective, whereas untreated controls developed consid- 
erable mold. 

In addition to the materials which are individiially 
enumerated above, other items were tested such as a 
fungicidal paint, glass coated with a fungicidal lac- 
quer, and a fungicidal lens cleaning compound, but 
none of these showed any fungicidal properties in the 
tropical house test. 

94 TESTS UNDER SIMULATED TROPICAL 
CONDITIONS EMPLOYING MITE- 
FUNGUS POPULATIONS 

This test method, which has been used at the Uni- 
versity of Pittsburgh in evaluating performance of 
materials under tropical conditions, has been described 
in OSRD Report 5010.'® It has been indicated in 
Chapter 3 that this method was used in the prelimi- 
nary screening of contact fungicides for optical instru- 


ments. The reference report gives the statistical basis 
for the evaluation of these materials. The studies on 
optical instruments were begun by NDRC Section 
16.1 and were later transferred to TDAC. 

The test chambers used in this method are prepared 
by placing sterile sphagnum moss in the bottoms of 
containers and then inoculating them with mites and 
fungi. High humidities are maintained in these 
chambers. Test materials are placed on the bed of 
sphagnum, and observations are made at appropriate 
intervals. 

This test method was developed in order to furnish 
a realistic test procedure for optical instruments in 
which the mite factor was dominant. In the early in- 
vestigations on optical instruments as well as on other 
materials, considerable attention was directed to the 
role of mites in the deterioration process, particularly 
as agents by which fungus spores are distributed. Sub- 
sequent reports of field observations are not consistent 
with respect to the importance of mites in the infesta- 
tion of materials, and the results obtained by this 
method must be interpreted accordingly. 

The following were among the materials tested at 
the University of Pittsburgh. 

Experimental Binoculars Treated with 
Fungicidal Carbon-Silver Coating 

This carbon-silver coating was the same which was 
applied to the cellophane wrappers of the packaged 
fruit bars (see Section 9.2). Three pairs of binoculars 
with cases were used; different formulations of the 
coating were applied to the interiors of the cases and 
the interiors and exteriors of the instruments. The 
duration of the exposure was four weeks. 

Fungus growth was particularly abundant on the 
interiors of the cases, which indicates that the treat- 
ment was ineffective in the protection of the leather. 
Fungus growth was also present in varying degrees in 
the interiors of the instruments. However, this is ex- 
plained in part by the fact that the instruments were 
not sealed and the mites in the test chambers would 
have had easy access to the interior of the instruments 
and would thus infect them with fungus spores. This 
serves to emphasize the importance of sealing optical 
instruments. 

Comparatively little fungus growth was found on 
the treated exteriors of the binoculars and this would 
suggest that the carbon-silver coating may have some 
value in protecting the external surfaces of optical 
instruments. 


EXPOSURE TESTS EMPLOYING MITE-FUNGUS POPULATIONS 


77 


Neopeene-Coated Fibeeglas Cloth 

Three different samples of these materials were 
placed in the test chambers for a four-week period and 
the results indicated that these materials did not sup- 
port fungus growth. These results confirmed tests 
which had previously been made on similar materials. 

Expeeimental Clutch Facings 

These samples were prepared using various percent- 


ages of iron in iron-bronze powder mixes, and the 
principal observation to be made was the extent to 
which corrosion occurred. The materials were submit- 
ted by the Office of the Chief of Ordnance. The de- 
tailed formulations were not submitted. Upon return 
of the materials to the submitter, dynamometer tests 
were to be made to determine the extent to which real 
damage resulted from the/ exposure. 

One specific formulation proved to be less suscep- 
tible to corrosion than did the other formulations. 


Chapter 10 

RECOMMENDATIONS FOR FUTURE WORK 


10.1 INTRODUCTION 

W HEKEAS THE EOEEGOiNG chai)ters of this report 
have reviewed the problems of the tropical de- 
terioration of equipment and materials and the results 
of studies to develop methods to prevent such deterio- 
ration, this chapter outlines the problems which are 
still in need of further investigation for the following 
materials : textiles and cordage, electric and electronic 
equipment, synthetic resins, plastics, and plasticizers, 
and photographic equipment and supplies. The aspects 
of the prevention of tropical deterioration of optical 
instruments and the coordination of test methods on 
which further information is needed are given in 
(’hapters 3 and 8 respectively. 

At the termination of the activities of the Tropical 
Deterioration Administrative Committee, the individ- 
ual subcommittees submitted recommendations which 
were concerned with problems for future investigation. 
The recommendations as given here are those which 
were made by the several subcommittees. 

10 2 RECOMMENDATIONS OF THE SUB- 
COMMITTEE ON TEXTILES 
AND CORDAGE 

1. The effect of light on the decomposition of 
cellulose should l)e undertaken as a fundamental study 
to provide data for use in formulating applications to 
prevent light deterioration as well as biological deteri- 
oration. 

2. Research directed toward a modification of the 
chemical structure of cellulose to increase its resist- 
ance to micro])iological attack should be encouraged. 

3. The use of synthetic fibers, such as Nylon and 
Viuyon, which are inherently resistant to micro])io- 
logical deterioration, should he encouraged wherever 
possible in military equipment which might be used 
in tropical areas. 

4. Research should he continued on fungicides and 
applications for textiles and cordage equipment to be 
used in tropical areas. Particular attention should be 
directed toward a search for fungicidal materials 
which are nontoxic to humans. 

5. Further work should be encouraged to deter- 


mine the mechanism of biological deterioration of 
natural fibers in order that the development of formu- 
lations to prevent this action could be approached with 
better understanding. 

It is indeed gratifying that investigations on all of 
the above problems are among those which were rep- 
resented in February 1946 in the research program 
of the Military Planning Division of the Office of the 
Quartermaster General. 


J0.3 RECOMMENDATIONS OF THE SUB- 
COMMITTEE ON ELECTRICAL AND 
ELECTRONIC EQUIPMENT 

1. Investigations should be conducted on basic ma- 
terials used in electronic equipment to determine their 
loss of properties with the absorption of water, wet- 
tability of surface, dimensional stability, and their 
susceptibility to fungal attack. 

2. Investigations should be carried on to develop 
coating materials which will form a nonwettable sur- 
face on solid dielectrics. 

3. The fungus-proofing of cotton for electrical uses 
should be investigated by its structural modification 
or by the addition of inhibitory chemicals to the cot- 
ton fll)ers in the thread-spinning process with the con- 
sideration that such treatments would be more durable 
and effective than the addition of fungicides to the 
wire finish. 

4. The validity of test methods and standards used 
in specifications should be subjected to laboratory in- 
vestigations and correlated with a condition of elec- 
trical stress and actual service life. The expected 
service life under humid tropical conditions of various 
components and assembled communications equipment 
should be determined. 

5. Reports should be obtained from personnel who 
operated or reconditioned electronic communications 
equipment that was under conditions of excessive hu- 
midity, giving their commendations for exceptional 
good performance of specific equipments and compo- 
nents and desired improvements in design and engi- 
neering for use under such conditions. 

6. Systematic maintenance practices for electronic 


78 


RECOMMENDATIONS FOR FUTURE WORK 


79 


field equipment should be developed for use under 
conditions of excessive dampness. 

7. An electrical measurement should be developed 
which will give a quantitative measure of degradation 
and be applied to electrical components which have 
been subjected to standard fungus tests as a required 
part of the procedure. 

8. Liaison and coordination should be continued 
between the various branches of the Services that are 
investigating and engineering electronic communica- 
tions equipment for use in tropical and arctic climates. 

10 4 RECOMMENDATIONS OF THE SUB- 
COMMITTEE ON SYNTHETIC RESINS, 
PLASTICS, AND PLASTICIZERS 

This subcommittee recommended that investiga- 
tions on the deterioration of plastics be continued to 
provide information on the following broad problems : 

1. The susceptibility of the basic components of 
plastic materials to fungus attack. 

2. The effects of fungi and moisture on properties 
of plastics, mechanical as well as electrical. 

3. The sterilization of plastic materials to eliminate 
contaminating organisms on control specimens in in- 
vestigations of physical and electrical properties. 

4. The incorporation of fungicides in plastic com- 
positions to provide permanent protection during the 
service life of the products. 

10 5 RECOMMENDATIONS OF THE SUB- 
COMMITTEE ON PHOTOGRAPHIC 
EQUIPMENT AND SUPPLIES 

1. Investigation and background research should 
be continued in the study of component and constit- 
uent materials for photographic uses. This should in- 
clude a study of the changes in all pertinent physical 


properties of such materials due to moisture, tempera- 
ture, the action of fungi, and other deteriorating 
agents of the tropics. 

2. The program should be carried on to coordinate 
the results of laboratory investigations and particu- 
larly test methods with actual deterioration in the 
field, with the end in view of providing a fundamental 
basis for comparing the deterioration produced in test 
chambers with the deterioration that occurs in the 
field under natural tropical conditions and ultimately 
standardizing the test methods used. 

3. Data should be collected upon the performance 
of equipment under tropical conditions to establish 
the relationship between performance degradation and 
physical deterioration and to determine suitable oper- 
ational ranges for all classes of photographic equip- 
ment and supplies. 

4. Continued study should be devoted to obtaining 
the best possible coating materials and preservatives 
needed to insure adequate tropic-proofing and to pro- 
long the service life of photographic materiel under 
field conditions. 

5. A program should be initiated to investigate the 
nonnutrient, waterproof, substitute synthetic mate- 
rials to replace gelatin in film and in filter manufac- 
ture. Included in this study should be the investiga- 
tion of appropriate dyes to be used with new media 
and the improvement of the support materials them- 
selves. 

6. Further attention should be directed to improve 
and simplify the design and construction of cameras, 
etc., in order to allow for ready interchangeability of 
parts and to make field maintenance easier under trop- 
ical operating conditions. Provisions should be made 
to include protective and preservative features wher- 
ever necessary. 

7. More efficient and expedient procedures and tech- 
niques to be used in the field maintenance problems 
under tropical conditions should be developed. 







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BIBLIOGRAPHY 


Numbers sucli as TD-100-]\12 indicate tliat the document listed has been microfilmed and that its title appears in 
the microfilm index i)rintcd in a separate volume. For access to the index volume and to the microfilm, consult the 
Army or Navy agency listed on the reverse of the half-title page. 


Chapler 2 

1. Handbook of Some Fungi Associated with Tropical Deteriora- 

tion, Leland Shanor, OSRD 6267, OE]\Isr-1356, George 
Washington University, Oct. 1945. TD-100-M2 

2. Tropical Fungus Culture Collection, William H. Weston, 

OSRD 5681, OE]\Isr-1389, Harvard University, Oct. 31, 
1945. TD-100-M3 

3. Studies of the Deterioration of Textiles under Tropical Con- 

ditions in the Canal Zone, Elso S. Barghoorn, OSRD 4807, 
Apr. 1945. TD-101.1-M2 

4. A Preliminary List of Micro-organisms ivhich Cause Damage 

to Ordnance Stores in India, with Particular Reference to 
Tentage and Cordage, Technical Report BIO/45/5 Con- 
troller General of Inspection, Great Britain, 1945, pp. 
418-425. TD-lOO-Ml 

5. The Role of Bacteria in the Deterioration of Cotton Duck, 

Under Tropical Conditions, Herbert W. Reuszer, OSRD 
4806, Apr. 1945. TD-lOl.l-Ml 

6. Bacteria Culture Collection, Herbert W. Reuszer, OSRD 

5682, OEMsr-1484, Alabama Agricultural Experiment 
Station, Oct. 31, 1945. TD-100-M4 

7. The Microbiological Degradation of Cotton Fabrics — Investi- 
gatioyis Conducted at the Quartermaster Tropical Deteriora- 
tion Research Laboratory, Ralph G. H. Siu and W. Lawrence 
White, Research and Development Branch, Military 
Planning Division, Office of the Quartermaster General, 
Dec. 31, 1945. 


Chapter 3 

1. Prevetdion of Deterioration of Optical Inslrumods in the 

Tropics, OSRD 6055, Subcommittee on Oi)tical Instru- 
ments, Tropical Deterioration Administrative Committee, 
Oct. 15, 1945. TD-102.3-M7 

2. The Tropic Proofing of Optical Instrunmds, Part I — The 

Value of Merthiosal as an Internal Fungicide, Tropic 
Proofing Committee, Scientific Instruments and Optical 
Panel, Australian Ministry of Munitions [Australia], 
July 1944. TD-102.3-M3 

3. The Fungus Fouling of Optical Instruments, W. G. Hutch- 

in.son, OSRD 4118, Division 16, Report 51, University of 
Pennsylvania, Sept. 30, 1944. TD-101.5-M3 

4. Report on Tropic Proofing, British Ministry of Sup|)ly, 

Feb. 1945. TD-102-M1 

5. “Deterioration of Glass in Tropical Use,’’ Frank L. Jones, 
Journal of the American Ceramic Society, Vol. 28, No. 1, 
Jan. 1945, p. 32. 

6. Minutes of Conference on Research Conducted in the Canal 
Zone on the Fouling of Optical Instrinnents, OSRD 1833, Di- 
vision 16, Report 29, NDRC, July 27, 1943. TD-101.5-M1 

7. Tropical Deterioration in Optical Instruments, OSRD 5767, 

OEMsr-871, Division 16, Ileport 97, University of Pitts- 
burgh, Apr. 17, 1945. Tr)-101.5-M4 

8. The Effect of Mites on Optical Instrumerds in the Tropics, 
I. G. Campbell, Report 4, War Office, Directorate of Me- 
chanical Engineering [Great Britain]. TD-101.5-M2 


9. Laboratory Investigations of Mould Growth in Optical In- 
struments, I. G. Campbell, Report 3, War Office, Direc- 
torate of Mechanical Engineering [Great Britain]. 

TD-101.5-M8 

10. The Mould Proofing of Leather Equipment for Services in the 
Tropics, I. G. Campbell, Report 2, War Office, Directorate 
of IMechanical Engineering [Great Britain]. 

TD-102.4-M1 

11. Cleaning of Optical Elements, Optical Shop Bulletin No. 7 
Engineering Section, Fire Control Sub-Office, Frankford 
Arsenal, Philadelphia, Pa., July 21, 1943. 

12. Further Studies on the Fouling of Optical Instruments, W. G. 

Hutchinson, OSRD 5684, OEMsr-205, University of Penn- 
sylvania, Oct. 31, 1945. TD-101.5-M7 

13. Methods of Prevention of Fungus Fouling of Optical Instru- 
ments in the Canal Zone, OSRD 3952, OEMsr-205, Division 
16, Report 46, University of Pennsylvania, July 25, 1944. 

TD-102.3-M4 

14. Cresatin as a Treatment for Fungus Proofing of Optical In- 
struments, OSRD 3803, OEMsr-205, Division 16, Report 
44, University of Pennsylvania, June 25, 1944. 

TD-102.3-M2 

15. Cresatin, Its Effect on Fire Control Instrument Materials, 
M. Frager, Frankford Arsenal, Philadelphia, Pa. 

16. Report on Binoculars Fitted with Cresatin, OSRD WA-4473- 

4B, Optical Instruments Panel, British Ministry of Sup- 
ply, May 26, 1945. TD-102.3-M6 

17. A Method for the Prevention of Mould Growth on Optical 

Instruments Exposed to Tropical Conditions, OSRD 4371, 
OEMsr-871, Division 16, Report 92, University of Pitts- 
burgh, Dec. 5, 1944. TD-102.3-M5 

18. Tropic Testing, OSRD 5010, OEMsr-871, Division 16, 
Report 96, University of Pittsburgh, Mar. 27, 1945. 

TD-101-M3 

19. Results of an Investigation Carried Out by the Government 

Chemists Department on the Corrosion of Metals by Thanite 
Liquid and Vapour, Conference on Tropical Proofing, OSRD 
WA-4369-2D, Optical Instruments Panel, British Ministry 
of Supply, Apr. 17, 1945. TD-101.6-M1 

20. Mildew Resistant Treatment for Optical Instruments, R. E. 
Vicklund, Report 917, Engineer Board, Mar. 10, 1945. 


Cliapk'r 1 

1. Bibliogra phy of Textiles and Cordage, Service Project .\N- 
14, Report 7, Tropical Deterioration Information Center, 
George Washington University, Dec. 1944. TD-102.1-M1 

2. Fungus Proofing of Textiles and Cordage for Use in Tropical 

Service, Leland Shanor and the Subcommittee on Textiles 
and Cordage, OSRD 4513, Jan. 1945. TD-102.1-M2 

3. Studies of the Deterioration of Textiles under Tropical Con- 

ditions in the Canal Zone, Elso S. Barghoorn, OSRD 4807, 
Apr. 1945. TD-101.1-M2 

4. Tropical Fungus Culture Collection, William H. Weston, 

OSRD 5681, OEMsr-1389, Harvard University, Oct. 31, 
1945. TD-100-M3 


81 


82 


BIBLIOGRAPHY 


5. The Role of Baeleria in the Deterioration of Cotton Daek 
Under Tropical CoynlUions, Herbert W. Reiiszer, OSRD 
4806, Apr. 1945. TD-lOl.l-Ml 

0. Bactena Cullnre Collection, Herbert W. Reuszer, OSRD 

5682, OEMsr-1484, Alabama Agricultural Experiment 
Station, Oct. 31, 1945. TD-100-M4 

7. Studies on the Effect of Aeration and Nutrition on Cellulose 
Decomposition by Certain Bacteria, Elwyn T. Reese, Re- 
search and Development Branch, Military Planning Di- 
vision, Office of the Quartermaster General, Mar. 1, 1946. 

8. The Microbiological Degradation of Cotton Fabrics — Investi- 
gations Conducted at the Quartermaster Tropical Deteriora- 
tion Research Laboratory, Ralph G. H. Siu and W. Lawrence 
White, Research and Development Branch, Military Plan- 
ning Division, Office of the Quartermaster General, Dec. 
31, 1945. 

9. Sumnmry of Work on Tropical Deterioration of Textiles, 
January 1945 to March 1946 inclusive, William D. Appel, 
National Bureau of Standards, Apr. 11, 1946. 

TD-101.1-M6 

10. The Effect of Ultraviolet Light on Cotton Cellulose and Its 
Influence on Subsequent Degi'adation by Microorganisms, 
R. P. Wagner, Harold H. Weber, and Ralph G. H. Siu, 
Research and Development Branch, Military Planning 
Division, Office of the Quartermaster General, Mar. 1, 
1946. 

11. “Fungus and Moisture Protection,” R. Proskauer and 
H. E. Smith, Electronics, 1945, Vol. 18, pp. 119-123. 

12. “Fungus Growths and Electric Apparatus,” A. C. Titus, 
General Electric Review, Aug. 1945, Vol. 48, pp. 19-22. 

Chapter 5 

1. The Problem of Fungal Growth on Synthetic Resins, Plastics 
and Plasticizers, Alfred E. Brown, OSRD 6067, Tropical 
Deterioration Administrative Committee, Oct. 1945. 

TD-101.2-M3 

2. F ungus Resistance of Plastics, R. H. Wellman and S. E. A. 

McCallan, OSRD 5683, OEMsr-1425, Bakelite Corp., 
Sept. 30, 1945. TD-101.2-M2 

3. Mildew Tests of Pure Plastics and Plasticizers, National 
Bureau of Standards, Washington, D. C., May 19, 1945. 

4. Data taken from various reports of the British Ministry 
of Supply. 

5. Tropical Deterioration of Materials for Electronic Equip- 
ment, Part I — Plasticizers, Report P-2492, Naval Research 
Laboratory, Bellevue, D. C., Apr. 4, 1945. 

6. Fungicides for Plastics, Fungus Resistance Tests, L. V. 
Larsen and W. Goss, General Electric Co., Pittsfield, 
Mass., Oct. 13, 1944. 

7. 1945 Plastics Catalogue, Plastics Catalogue Corp., New 
York, N. Y. 

8. Tropical Test Program, Part I — Materials, Sperry Gyro- 
scope Co., Inc., Brooklyn, N. Y., June 14, 1944. 

9. Data from test reports made available at Materials Labo- 
ratory, Navy Yard, Brooklyn, N. Y. 

10. Lectures on Tropicalization, Inspection Manual Section, 
SCGSA, Fort Monmouth, N. J., Nov. 9, 1944, Chapter 
entitled “Plastics,” by N. Vasileff, p. 21. 

11. Test data from Signal Corps Laboratory, Fort Monmouth, 
N. J. 

12. Report on Tropic Proofing, British Ministry of Supply, 

Feb. 1945. TD-102-M1 

13. Physical Properties of Laminates Contaming Salicylanilide, 
L. V. Larsen and W. Goss, General Electric Co., Pittsfield, 
Mass., Sept. 1945. 

14. Data furnished by H. E. Smith, Insl-X Co., and A. D. 
King, Plasticides, Inc. 


15. Patch Testing to Determine the Irritant and Bensitization 
Properties of Various Materials, Medi(*al Field Research 
Laboratory, Camp Le Jeune, N. C., Mar. 6, 1945. 


Chapter 6 

1. Summary Report of the Subcommittee on Photographic 

Equipment and Supplies, OSRD 6218, Service Project 
AN-14.2, Tropical Deterioration Administrative Com- 
mittee, Oct. 1945. TD-101.5-M5 

2. The Fungus Fouling of Photographic Film, J. A. Jump and 
W. G. Hutchinson, OSRD 5685, OEMsr-205, The Johnson 
Foundation, University of Pennsylvania, Oct. 31, 1945. 

TD-101.5-M6 

3. Report on Trip to Panama October 7 to November 11, 194Jf., 

W. G. Hutchinson, Nov. 1944. TD-101-M2 

4. The Use of Merthiosal in Aircraft Cameras, P. G. Law, 

OSRD II-5-6450(S), Technical Paper 969, University of 
Melbourne, Australia, May 5, 1944. TD-102.3-M1 


Chapter 7 

1. Failure of Electronie Equipment under Tropieal Service 
Conditions, J. M. Leonard, Naval Research Laboratory, 
Bellevue, D. C., Feb. 20, 1945. 

2. Report on Tropic Proofing, British Ministry of Supply, 

Feb. 1945. TD-102-M1 

3. “Tropical Failures of Electronic Equipment,” Electronics, 
Sept. 1944, p. 198. 

4. “Effect of Fungi on Electronic Equipment,” W. F. Horner 
and Helen M. Coulon, Radio Electronic Engineering, Jan. 
1945. 

5. This is Serious — Tropicalization, Signal Corps, U. S. Army. 

6. Tropical Maintenance of Ground Signal Equipment, War 
Department Technical Bulletin SIG 72, Aug. 9, 1944. 

7. Moisture and Fungus Proofing of Signal Equipment, Marine 
Corps Technical Bulletin 123, Aug. 1, 1944. 

8. The Combatting of Mould Growth on Service Electronic 

Equipment, A. F. Parker-Rhodes, OSRD WA-5009-5, 
Report 968, Signal Research and Development Establish- 
ment [Great Britain], July 1945. TD-102.2-M2 

9. Recommendations and Information for Tropicalization of 
Ground Signal Equipment (Memorandum), Signal Corps 
Ground Signal Agency, Fort Monmouth Signal Labora- 
tory, Fort Monmouth, N. J., Apr. 17, 1944. 

10. Fungus Growth on Hookup Wire, R. H. Luce and Warren C. 

Stoker, OSRD 5692, OEMsr-1488, Rensselaer Polytechnic 
Institute, Oct. 31, 1945. TD-101.3-M3 

11. The Effect of Moisture and Fungus on Electrical and Me- 
chanical Properties of Plastic Insulating Materials, OSRD 
6324, OEMsr-1479, Johns Hopkins University, Oct. 1945. 

TD-101.2-M4 

12. Insulation Measurements on Solid Dieleetrics with Particular 

Reference to Insulating Varnishes, OSRD II-5-6635(s), 
Report 142, Munitions Supply Laboratories, Ministry of 
Munitions [Australia], Feb. 1945. TD-101.4-M1 

13. Effect of Moisture and Fungus on Electrical Insulating Ma- 

terials, OSRD 5691, OEMsr-1479, Johns Hopkins Uni- 
versity, Oct. 1945. TD-101.3-M1 

Chapter 8 

1. Methods of Testing Biological Deterioration of Service Ma- 
terials, OSRD 6056, Subcommittee on Coordination of 
Test Methods, Tropical Deterioration Administrative 
Committee, Oct. 15, 1945. TD-101.1-M4 


BIBLIOGRAPHY 


83 


2. Studies on Methods of Testing Hookup Wires for Resistance 
to Fungus Attack, W. G. Hutchinson, OSRD 5686, 
OEMsr-205, University of Pennsylvania, Oct. 31, 1945. 

TD-101.3-M2 

3. Studies on Methods of Testing Coating Materials for Resist- 
ance to Fungus Attack, W. G. Hutchinson, OSRD 5687, 
OEi\Isr-205, University of Pennsylvania, Oct. 31, 1945. 

TD-101.4-M2 

4. Development of a Method for Testing the Resistance of Plas- 
tics to Fimgus Attack, W. G. Hutchinson, OSRD 5688, 
OEI\Isr-205, University of Pennsylvania, Oct. 31, 1945. 

TD-101.2-M5 

5. Fungus Resistance of Plastics, R. H. Wellman and S. E. A. 

xMcCallan, OSRD 5683, OEI\Isr-1425, Bakelite Corp., 
Sept. 30, 1945. TD-101.2-M2 

6. Conference on Biological Testing and Test Organisms, Tex- 

tile and Cordage Meeting, Paul B. Marsh, J. D. Dean, and 
others. Service Project AN-14, Tropical Deterioration Ad- 
ministrative Committee, Apr. 17, 1945. TD-101.1-M3 

7. Studies on Pure-Culture Methods of Testing Fungus Deterio- 
ration of Textiles, W. G. Hutchinson, OSRD 5689, OEMsr- 
205, University of Pennsylvania, Oct. 31, 1945. 

TD-101.1-M5 

8. The Microbiological Degradation of Cotton Fabrics — Investi- 
gations Conducted at the Quartermaster Tropical Deteriora- 
tion Research Laboratory, Ralph G. H. Siu and W. Lawrence 
White, Research and Development Branch Military 
Planning Division, Office of the Quartermaster General, 
Dec. 31, 1945. 

Chapter 9 

1 . The Tropical Deterioration Testing Station at Barro Colorado 
Island, W. G. Hutchinson, Spencer H. Davis, Jr., and J. A. 
Jump, OSRD 5690, OEMsr-205, The Johnson Foundation, 
University of Pennsylvania, Oct. 31, 1945. TD-101-M4 


2. Minutes of the Meeting of the Subcommittee on Synthetic 
Resins, Plastics and Plasticizers, Tropical Deterioration 
Administrative Committee, Alfred E. Brown, June 6, 1945. 

TD-101.2-M1 

3. Interim Report on Moist Tropical Exposure of Tropicalized 

Phenol Plastic Terminal Strips, Subcommittee on Electrical 
and Electronic Equipment, Tropical Deterioration Ad- 
ministrative Committee, NDRC and Ordnance Depart- 
ment, U. S. Army, Apr. 12, 1945. TD-102.2-M1 

4. Further Studies on the Fouling of Optical Instruments, 
W. G. Hutchinson, OSRD/ 5684, OEMsr-205, The Johnson 
Foundation, University of Pennsylvania, Oct. 31, 1945. 

TD-101.5-M7 

5. Studies on Methods of Testing Coating Materials for Resist- 

ance to Fungus Attack. W. G. Hutchinson, OSRD 5687, 
OEMsr-205, The Johnson Foundation, University of 
Pennsylvania, Oct. 31, 1945. TD-101.4-M2 

6. Development of a Method for Testing the Resistance of Plas- 

tics to Fungus Attack, W. G. Hutchinson, OSRD 5688, 
OEIVlsr-205, The Johnson Foundation, University of 
Pennsylvania, Oct. 31, 1945. TD-101.2-M5 

7. Studies on Methods of Testing Hookup Wires for Resistance 

to Fungus Attack, W. G. Hutchinson, OSRD 5686, OEMsr- 
205, The Johnson Foundation, University of Pennsvlvania, 
Oct. 31, 1945. TD-101.3-M2 

8. A House for the Study of Materials under Tropical Con- 
ditions, W. G. Hutchinson and Robert McCrea, OSRD 
4048, OEMsr-205, Division 16, Report 49, The Johnson 
Foundation, University of Pennsylvania, July 25, 1944. 

TD-lOl-Ml 

9. Fungus Resistance of Plastics, OSRD 5683, OEMsr-1425, 

Bakelite Corp., Sept. 30, 1945. TD-101.2-M2 

10. Tropical Testing, OSRD 5010, OEMsr-871, Division 16, 
Report 96, University of Pittsburgh, Mar. 27, 1945. 

TD-101-M3 


OSRD APPOINTEES 


Chairman 

Gustavus J. Esselen 

Technical Aide 

Charles Heimsch 

Special Assistant 

Lt. Wesley H. Suit 

Members 
Frank L. Jones 
P. K. McElroy 
Gordon Osborne 
E. A. Throckmorton 

Subcommittees 

COORDINATION OF TEST METHODS 
Chairman 

Selman a. Waksman 
M embers 

H. D. Barker Walter N. Ezekiel, Naval Ordnance Laboratory 

O. B. Hager Lt. Col. W. J. Slagle, Chemical Warfare Service 

John Leutritz Captain R. D. Wells, Office of the Quartermaster General 

L. M. Ames, The Engineer Board W. Lawrence White, Philadelphia Quartermaster Depot 

ELECTRICAL AND ELECTRONIC EQUIPMENT 

Chairman 
K. G. Compton 

M embers 

P. K. McElroy Commander William I. Bull, Bureau of Ships 

A. C. Titus Major A. M. Dickie, Office of the Chief of Ordnance 

R. W. Waring Lt. Col. R. J. Framme, Air Technical Service Command 

Lt. a. 11 . Blackmore, Bureau of Aeronautics R. S. Glasgow, Office of the Chief Signal Officer 

Lt. Col. R. H. Noyes, Signal Corps 


OPTICAL INSTRUMENTS 

Chairman 
Frank L. Jones 

M embers 

George Arnold John J. Lippoth 

Theodore Dunham, Jr. John Pittman 

Lt. R. E. Vicklund, The Engineer Board 


OSKD APPOINTEES, contwued. 


rilOTOGRAPllIC EQUIPMENT AND SUIU^LIES 
Chairman 

W. H. Offenhauser, Jr. 

Vice Chairman 

J, G. Hildebrand, Jr. 

George Arnold 
James Forrestal 
Glenn E. Matthews 
V. B. Sease 


Members 

Lt. Commander L. M. Bearing, Bureau of Aeronautics 
Major L. T. Goldsmith, Signal Corps Photographic Center 
Major John T. Parker, Air Technical Service Command 
Lt. R. E. Vicklund, The Engineer Board 


SYNTHETIC RESINS, PLASTICS AND PLASTICIZERS 

Chairman 

Gordon M. Kline 

A. D. King 
L. V. Larsen 
A. E. Maibauer 


Members 

R. W. ^^"ARING 

Lt. Col. L. H. Hitchcock, Signal Corps 

Lt. a. H. Lightbody, Naval Ordnance Laboratory 


TEXTILES AND CORDAGE 

Chairman 

Milton Harris 


\V. D. Appel 
H. D. Barker 
Kenneth H. Barnard 
R. F. Tener 


Captain T. F. Cooke, The Engineer Board 


Members 

Major A. M. Dickie, Ofhee of the Chief of Ordnance 
V. P. Giddings, Jr., Corps of Engineers 
William Lee, Office of the Quartermaster General 
Captain R. D. Wells, Office of the Quartermaster General 
Lt. W. P. Whitlock, HI, Bureau of Ships 


35 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECTS OF CONTRACTS 


Contract Name and Addres.s 

Number of Contractor 

Subject 

OEIMsr-205 The Trustees of the University of Pennsylvania 

Philadelphia, Pennsylvania 

Tropical deterioration of optical 
glass, exposure tests on other 
equipment, and coordination 
of test methods. 

OEIMsr-871 The University of Pittsburgh 

Pittsburgh, Pennsylvania 

Exi)osurc tests of instruments 
and equipment under tropical 
conditions. 

OEMsr-1313 D. D. Berolzheimer 

50 E. Forty-first Street, New York, N. Y. 

Search of literature on tropical 
deterioration. 

OEMsr-1356 The George Washington University 

Washington, D. C. . 

Information Center and surveys 
in the field of tropical de- 
terioration. 

OEMsr-1389 President and Fellows of Harvard College 

Cambridge, Massachusetts 

Maintaining a Tropical Fungus 
Culture Collection. 

OEMsr-1425 Bakelite Corporation 

New York, N. Y. 

Troj)ical deterioration of 
plastics. 

OEMsr-1479 The Johns Hopkins University 

Baltimore, Maryland 

Deterioration of electrical insu- 
lating materials by molds and 
moisture. 

OEMsr-1484 The Agricultural Experiment Station of the Alabama Polytechnic Institute 
Auburn, Alabama 

Maintaining a Bacteria Culture 
Collection. 

OEMsr-1488 Rensselaer Polytechnic Institute 

Troy, New York. 

Fungus growth on hookup wire. 


86 


SERVICE PROJECT NUMBERS 


The projects listed below were transmitted to the Office of the Execu- 
tive Secretary, OSRD, from the War or Navy Department through 
either the War Department Liaison Officer for NDRC or the Office 
of Research and Inventions (formerly the Coordinator of Research 
and Development), Navy Department. 


Service Project Number 


Subject 


AN-14 


Prevention of deterioration of materiel under tropical conditions. 


AN-14.1 


Fungus growth on hookup wires. (Requested by the Signal Corps.) 


AN-14.2 


Deterioration of photographic and X-ray film due to fungus, insects and moisture. (Requested 
by Headquarters, Army Service Forces, Maintenance Division.) 


87 




INDEX 


The subject indexes of all STR volumes are combined in a master index printed in a separate volume. For access 
to the index volume consult the Army or Navy Agency listed on the reverse of the half-title page. 


Airplane fabrics, coated, exposure tests, 
70 

Alabama Agriculture Experiment Sta- 
tion, 15 

American Association of Textile Chem- 
ists and Colorists, 67 
Association and interaction between 
fungi, 12 
Australia 

corrosion of optical glass by moisture, 
report, 18 
fungus cultures, 8 
mycological panel, 5, 8, 10, 14 

Bacteria Culture Collection of OSRD, 

15- 17 

cellulose-decomposing bacteria, 16 
cytophaga group, 16 
isolated bacteria identification, 15-17 
noncellulose-decomposing bacteria, 

16- 17 

Bacterial deterioration of textiles, 35-36 
cellulose-decomposing bacteria, 35-36 
frequency on exposed samples, 35-36 
noncellulose-decomposing bacteria, 
35 

Binoculars, exposure tests, 76 
Boyce Thompson Institute, 41, 47 
British research corrosion of optical 
glass by water, 18 

Brown, Alfred E., fungal growth on 
synthetic plastics, 40-48 

Camera equipment in tropics, 54-56 
design recommendations for warfare, 
5,5-56 

deterioration of the camera, 54-55 
lens protection, 54 

Chlorinated hydrocarbons, suscepti- 
bility to fungus, 42 
Coating materials, acceptance test, 64 
Copper napthenate, cotton fabric de- 
terioration, 36-37 
Cork, exposure tests, 73, 74 
Corrosion of optical glass 
by fungi, 18-20 
by moisture, 18-19 
Cotton fabrics, exposure tests, 72 
Cresatin (metacresyl acetate) for fun- 
gus control, 24-25 
Culture collections, bacteria, 15-17 
Culture collections, fungus 

see Tropica] Fungus Culture Collec- 
tions 

Curtis, H. L., insulating properties of 
solid dielectrics, 60 

Ear wardens, exposure tests, 72-76 
Electricandelectronicequipment, 57-60 


agents of deterioration, 57 
fungus growth on hookup wire, 58-60 
recommendations, 78-79 
remedies applied, 57-58 
Electrical insulating materials, effects 
of moisture and fungus, 60-61 
Exposure tests of materials (Panama), 
69-74 

coated airplane fabrics, 70 
cork samples, glue and resin bonded, 
73 

cotton fabrics, 72 
ear wardens, 72 
filter papers, treated, 71 
flying clothing material, 69 
gas masks, 72 

glass cord coated with fungicidal lac- 
quers and varnishes, 73 
hookup wires, 73 
neoprene earphone sockets, 73 
packaged fruit bars, 70 
paper message pads, 72 
plastic samples, 73 
plastic terminal strips, 72 
pouchette containers for ear wardens, 

73 

sheet insulating materials, 71 
shoes and stitched leather samples, 71 
steel panels with strippable coatings, 
72, 73 

Exposure tests of materials (Univ. of 
Pa.), 74-76 
ear wardens, 74 
felt samples, 76 

glue cork and packaged cork samples, 

74 

leather and fabric carrying case, 74 
leather cases, treated, 76 
leather from Japanese shoe, 75 
lenses, coated, 75 
plastic samples, 74 
Polaroid lenses, 75 
projection screen samples, 75 
seat cushion assembly, 75 
tropical house, 74 
vellumoid gaskets, 75 
Exposure tests of materials (Univ. of 
Pittsburgh), 76-77 
binoculars, treated, 76 
clutch facings, 77 

fiberglass cloth, neoprene-coated, 77 
test method employing mite-fungus 
population, 76 

Fabric treatments 

ground-contact exposure, 32 
overall protective action, 32 
soil-burial conditions, 32 
sun exposure, 32 
Fabrics, effect of light, 37-38 
Felt samples, exposure tests, 76 


Fenchyl thiocyanoacetate 
see Thanite 

Field studies of textile deterioration 
see Panama, field studies of textile 
deterioration 

Film consumption by armed forces for 
1945; 49 

Filter paper, treated, exposure tests, 71 
Flying clothing material, exposure tests, 
69 

Fungicides 

added to plastics, 46-48 
effectiveness, 37, 46-47 
health hazards, 48 
mercurial fungicides, 48 
salicylanilide, 47 
Fungus 

biological factors affecting resistance 
of plastics, 65-66 
cellulose digesting capacity, 32 
collections, 7-15 
corrosion of optical glass, 18-20 
cresatin as a control, 24-25 
effect on electrical insulating materi- 
als, 60-61 

effect on gelatin filters, 50 
growth on hookup wires, 58-60, 63-64 
growth on synthetic resins, plastics 
and plasticizers, 40-48 
inhibitory radiations for prevention, 
26 

photographic film for spotting, 53-54 
study and identification, 12 
textile test panels, 30-32 

Gas masks, exposure tests, 72 
Gelatin filters, tropical deterioration, 
50-51 

Glass cord, coated, exposure tests, 73 
Glue cork, exposure tests, 74 
Glycol derivatives, susceptibility to 
fungus, 42 

Harvard University, fungi identifica- 
tion, 12 

Hookup wire, fungus growth on, 58-60, 
73 

Hookup wire, fungus resistance test 
methods, 63-64 

Inhibitory radiations as fungus pre- 
ventive, 26 

Insulating materials, sheet, exposure 
tests, 71 

Laurie acid derivatives, susceptibility 
to fungus, 42 

Leather, exposure tests, 71, 74-76 
Leather binocular cases as fungus 
source, 21 

Lenses, exposure tests, 75 
Light, effect on fabrics, 37-38 


89 


90 


INDEX 


Materials testing, tropical 

see Exposure tests of materials 
Merthiosal (sodium ethylmercuri thio- 
salicylate) treatment in fungus 
control, 23, 24 

Metacresul acetate, see Cresatin 
Mites in optical instruments 
Cresatin for control, 24 
Merthiosal for control, 23 
significance in infection, 19 
Moisture 

accumulation by optical instruments, 
20-21 

effects on electrical insulating ma- 
terials, 60-61 

effects on gelatin filters, 50 
Mycological Panel of the Scientific 
Liaison Bureau (Australian), 5, 
8, 10, 14 

Neoprene earphone sockets, exposure 
tests, 73 

New Guinea science mission, 52 
Nonsporulating mycelia, 13 
Northern Regional Research Labora- 
tory, 11 

Nylon, exposure tests, 69, 71 
Nylon in film preservation, 54 

Oils, natural and synthetic, suscepti- 
bility to fungus, 44 
Oleic acid derivatives, susceptibility to 
fungus, 42 
Optical glass 

corrosion by fungus, 18-20 
corrosion by moisture, 18-19 
Optical instrument deterioration, con- 
trol, 21-26 

chemical control, 23-26 
cleaning and repairing, 21 
Cresatin, 24-25 

dehumidification and sealing, 22-23 
fungicides, 21 
general considerations, 21 
improved storing conditions, 22-23 
inhibitory radiations, 26 
Merthiosal treatment, 23 
mites, 23 
jdastic cases, 21 

recommendations for new design, 26 
Roccal, 23 

sanitation methods, 21 
sealing compounds, requirements, 21 
Thanite treatment, 25-26 
Optical instruments repair and storage, 
18, 21, 22 

Organisms associated with tropical de- 
terioration, 7-17 

bacteria culture collection, 15-17 
tropical fungus culture collection, 
7-15 

Packaged fruit bars, exposure tests, 70 
Panama, cultures from, 9 
Panama, exposure tests, of materials 
see Exposure tests of materials 
( Panama) 


Panama, field studies of textile deteri- 
oration, 28-35 
climatic characteristics, 28 
conclusions after 16 weeks exposure, 
32-33 

conclusions after 60 weeks exposure, 
33 

exposure plan, 29 

fabric treatments, relative efficacy, 32 
fungus observations, 30-32 
materials used, 28-29 
mycological factors, 29 
tensile strength loss, 33-34 
Panama Science Mission, 15, 35, 52 
Paper pads, exposure tests, 72 
Pentaerythritol derivatives, suscepti- 
bility to fungus, 43 
Pestalotia, 30, 31 

Phosphic acid derivatives, suscepti- 
bility to fungus, 43 

Photographic equipment and supplies, 
tropical deterioration, 49-56 
cameras, 54-55 
consumable supplies, 50-54 
containers, 51-52 
design improvements, 55 
film, 52-54 

film consumption by Armed Forces 
for 1945; 49 

letter excerpts from signal corps 
photographers, 49 
nature of problem, 49-50 
nonconsumable supplies, 54-56 
organization of program, 50 
packaging, 51-52 
paper, 51 

recommendations, 79 
storage conditions, 55 
Phthalic acid derivatives, susceptibility 
to fungus, 43 

Plastic compositions, susceptibility to 
fungal attack, 45-46 
laminated materials, 45 
molded pieces, 46 
thermoplastics, 46 
Plastics 

addition of fungicides, 46-48 
exposure tests, 72-74 
fungi-static, 46-48 
recommendations, 79 
sterilization, 45 

Plastics, fungus test methods, 64-66 
biological factors in determining 
fungus resistance, 65-66 
comparisons of edges and surfaces, 65 
duration of test period, 64 
inoculation of samples, 65 
nutrients, addition of, 65 
quantitative methods, 64 
recommended method, 65 
unreliable methods, 64 
Plasticizers, susceptibility to fungal at- 
tack, 41-45 
abietic acid, 45 

aliphatic dicarboxylic acid deriva- 
tives, 41 

aliphatic esters, 44 
aromatic esters, 45 


aromatic hydrocarbons, 45 
fatty acid derivatives, 41 
glycol and glycolic acid derivatives, 
41 

pentaerythritol esters, 41 
phosphoric acids, 41 
phthalic acid derivatives, 44 
thermoplastic materials, 41 
toluenesulfonic acid derivatives, 45 
Prevention of tropical deterioration of 
materials, early studies, 5 
Pullularia, 30-31 
Puratize N5-X, 72 

Quartermaster laboratories, 8 
Quartermaster program, textile deteri- 
oration, 38-39 

Radioactive control of fungus in optical 
instruments, 26 

Recommendations for future work, 
78-79 

electrical and electronic equipment 
78 

photographic equipment and sup- 
plies, 79 

synthetic resins, plastic and plasti- 
cizers, 79 

textiles and cordage, 78 
Rensselaer Polytechnic Institute, 58 
Repair of optical instruments, 21 
Resin plasticizers, susceptibility to 
fungus, 43 

Resins, pure, fungal susceptibilitv, 
40, 41 

Ricinoleic acid derivatives, suscepti- 
bility to fungus, 43 

Roccal (high molecular alkyldimethyl- 
benz 3 d ammonium chrloridc^s), 
23, 53 

Rohm and Haas Co., 71 

Salicylanilide, fungal resistance, 47 
Scientific Liaison Bureau (Australian), 
5, 8, 14 

Sealing and dehumidification of optical 
instruments, 22-23 
Sealing compounds, 22-23 
Sebacic acid derivatives, susceptibility 
to fungus, 44 

Soil burial tests of textiles, 33 
Stearic acid derivatives, susceptibility 
to fungus, 44 

Sterilization of plastics, 45 
Storage conditions for {)hotographic 
equipment, 55 

Storage of optical instruments, 18, 22 
Synthetic plastic materials, fungal sus- 
ceptibility, 40-48 
recommendations, 79 

TDAC program, 6 

Tensile strength loss in exposed textiles, 
33-34 

TFCC 

see Tropical Fungus Culture Collec- 
tion 


INDEX 


91 


'resting materials iiiuler tr()i)ical condi- 
tions, results 

see Exposure tests of materials 
Test station, tropical, 69 
Test-method studies, tropical deterio- 
ration, 62-68 
coating materials, 64 
evaluation of test results, 68 
hookup wires, 63-64 
I)lastics, 64-66 
textiles, 67-68 

Textiles, tropical deterioration, 27-39 
bacteria, 35-36 
causes of deterioration, 27 
copper naphthenate, effect on cotton 
fabric, 36-37 
cotton sheeting, 29 
duck, 28-29 

exposures in Florida and New Guinea, 
34 

field studies in Panama, 28-35 
fungi test panels, 30-32 


fungicide mixtures, effectiveness, 37 
history of research, 27 
light, effect on fabrics, 37-38 
need for field studies, 28 
pure culture methods of testing, 67-68 
Quartermaster ])rogram, 38-39 
water repellant fabrics, 29 
Thanite treatment of optical instru- 
ments, 25-26 
corrosive action, 25 
field testing, 25 

recommendations for general use, 25 
Tropical Deterioration, Administrative 
Committee, 6 

Tropical deterioration, summary of 
volume, 1-4 

Tropical Fungus Culture Collection, 
7-15 

association and interaction between 
fungi, 12 

cultures distributed, 10 
frequency of representation, 13-14 


maintenance of cultures, 1 1 
new genera and species, 1 5 
nonsporulating mycelia, 13 
organisms in collection, 8-10 
purpose, 8 

separation of cultures, 10 
significance of samples, 15 
similar collections from different re 
gions, 14 

study and identification, 12 
Tropicaldest station, 69 


Ultraviolet light, effect on fabrics, 38 
^ University of Pa., exposure tests of 
materials 

see Exposure tests of materials (Univ. 
of Pa.) 

University of Pittsburgh, exposure tests 
of materials 

see Exposure tests of materials (Univ. 
of Pittsburgh) 



1. 





I 




J 




















